r.md

R

Race condition : The condition of an electronics, software, or other system where the system’s substantive behavior is dependent on the sequence or timing of other uncontrollable events. It becomes a bug when one or more of the possible behaviors is undesirable. A race condition can be difficult to reproduce and debug because the end result is non-deterministic and depends on the relative timing between interfering threads. Problems that occur when using systems can therefore disappear when running in debug mode, when additional logging is added, or when attaching a debugger, often referred to as a “Heisenbug.” It is therefore better to avoid race conditions by careful software design. The term “race condition” was already in use by 1954. †

Race hazard : → Race condition

RACI matrix : → Responsibility Assignment Matrix

RADIUS : → Remote Authentication Dial-In User Service

Rails : → Ruby on Rails

Raku : A member of the Perl family of programming languages. Formerly known as Perl 6, it was renamed in 2019. Raku introduces elements of many modern and historical languages. Compatibility with Perl was not a goal, though a compatibility mode is part of the specification. The design process for Raku began in 2000. † ℹ︎ raku.org

RAM : → Random-Access Memory : → Responsibility Assignment Matrix

Random variable : A variable whose values depend on outcomes of a random phenomenon. The formal mathematical treatment of random variables is a topic in probability theory. In that context, a random variable is understood as a measurable function defined on a probability space whose outcomes are typically real numbers. †

Random-Access Memory : A form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory, in contrast with other direct-access data storage media. †

Ranking : A relationship between a set of items such that, for any two items, the first is either ranked higher than, ranked lower than, or ranked equal to the second. In mathematics, this is known as a weak order or total preorder of objects. It is not necessarily a total order of objects because two different objects can have the same ranking. The rankings themselves are totally ordered. Search engines rank web pages by their expected relevance to a user’s query using a combination of query-dependent and query-independent methods. Query-independent methods attempt to measure the estimated importance of a page, independent of any consideration of how well it matches the specific query. Query-independent ranking is usually based on link analysis; examples include the HITS algorithm, PageRank, and TrustRank. †

Raster image : A dot matrix data structure that represents a generally rectangular grid of pixels (points of color), viewable via a monitor, paper, or other display medium. Raster images are stored in image files with varying formats. A raster is technically characterized by the width and height of the image in pixels and by the number of bits per pixel (or color depth, which determines the number of colors it can represent). Most computer images are stored in raster graphics formats or compressed variations, including GIF, JPEG, and PNG. †

Rate limiting : A measure to control the rate of requests sent or received by a network interface controller. Rate limiting can be used to prevent DoS attacks and to limit web scraping. †

Rax : A React framework for building universal applications. Rax is maintained by Alibaba. ℹ︎ rax.js.org

RCDATA : → Replaceable Character Data

RCS : → Revision Control System

RDBMS : → Relational Database Management System

RDF : → Resource Description Framework

RDF Site Summary : A web feed which allows users and applications to access updates to websites in a standardized, computer-readable format. These feeds can, for example, allow a user to keep track of many different websites in a single news aggregator. Websites usually use RSS feeds to publish frequently updated information, such as blog entries, news headlines, or episodes of audio and video series. An RSS document (called feed, web feed, or channel) includes full or summarized text, and metadata, like publishing date and author names. †

RDP : → Remote Desktop Protocol

RDSMS : → Relational Data Stream Management System

React : A JavaScript library for building user interfaces. React was first released in 2013 and is maintained by Facebook and a community of individual developers and companies. React can be used as a base in the development of single-page or mobile applications. However, React is only concerned with rendering data to the DOM and so creating React applications usually requires the use of additional libraries for state management, routing, and interaction with APIs. † ℹ︎ reactjs.org

React Native : A mobile application framework first released in 2015 by Facebook. React Native enables to use the React library along with native mobile platform capabilities. †

Reactive Extensions for JavaScript : A library for the development of asynchronous and event-based programs, with helpers for asynchronous or callback-based code. ℹ︎ reactivex.io

Reactive Manifesto : A systems architecture approach in which it is declared necessary for systems to be responsive, resilient, elastic, and message-driven. Such systems are considered reactive systems. ℹ︎ reactivemanifesto.org

Reactive programming : A declarative programming paradigm concerned with data streams and the propagation of change. With this paradigm it is possible to express static (e.g., arrays) or dynamic (e.g., event emitters) data streams with ease, and also communicate that an inferred dependency within the associated execution model exists, which facilitates the automatic propagation of the changed data flow. Reactive programming has been proposed as a way to simplify the creation of interactive user interfaces and near-real-time system animation. †

ReactJS : → React

Read the Fucking Manual : The suggestion that one could have found more information or a solution to a problem in documentation. Initialisms similar to RTFM include “STFW” (“Search the Fucking Web”), “GIYF” (“Google Is Your Friend”), “DYOR” (“Do Your Own Research”), and “LMGTFY” (“Let Me Google That for You”). †

Read-Eval-Print Loop : A simple, interactive computer programming environment that takes single user inputs (i.e., single expressions), evaluates (executes) them, and returns the result to the user; a program written in a REPL environment is executed piecewise. The term is usually used to refer to programming interfaces similar to the classic Lisp machine interactive environment. Common examples include command-line shells and similar environments for programming languages. The technique is characteristic of scripting languages. †

Readability : The ease with which a reader can understand a written text. In natural language, the readability of text depends on its content (the complexity of its vocabulary and syntax) and its presentation (such as typographic aspects like font size, line height, and line length). Not to be confused with legibility. †

Reading disorder : → Dyslexia

README : A file that contains information about other files in a directory or archive of computer software. A form of documentation, it is usually a simple plain-text file called READ.ME, README.TXT, README.md (for a text file using Markdown), README.1ST, or just README. The file’s name is generally written in uppercase letters. †

Real User Monitoring : A passive monitoring technology that records all interaction of a user with a website, or of a client with a server or cloud-based application. Monitoring actual user interaction is important to operators to determine if users are being served quickly and without errors and, if not, which part of a business process is failing. Real user monitoring data is used to determine the actual service-level quality delivered to end users and to detect errors or slowdowns on websites. †

RealAudio : A proprietary audio format released in 1995 by RealNetworks. †

Really Simple Syndication : → RDF Site Summary

RealVideo : A suite of proprietary video compression formats first released in 1997 by RealNetworks. †

Recidivism : As an Agile metric, the total number of user stories completed in a Sprint that entered development for the second time divided by the total number of completed stories.

Recommendation : The World Wide Web Consortium (W3C) term for a specification or web standard.

Recovery Point Objective : The maximum time period of data loss acceptable in the event of an incident or failure.

Recovery Time Objective : The maximum period of downtime acceptable to restore from backup and to resume processing.

Recursion : A method of solving a problem where the solution depends on solutions to smaller instances of the same problem. Such problems can generally be solved by iteration, but this needs to identify and index the smaller instances at programming time. At the opposite, recursion solves such recursive problems by using functions that call themselves from within their own code. The approach can be applied to many types of problems, and recursion is one of the central ideas of computer science. † : → Recursion

Red, Green, and Blue : As the RGB color model, an additive color model in which red, green, and blue light are added together in various ways to reproduce a broad array of colors. The main purpose of the RGB color model is for the sensing, representation, and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography. RGB is a device-dependent color model: Different devices detect or reproduce a given RGB value differently, since the color elements (such as phosphors or dyes) and their response to the individual R, G, and B levels vary from manufacturer to manufacturer, or even in the same device over time. Thus an RGB value does not define the same color across devices without some kind of color management. †

Redesign : The process or outcome of a design update for a product or interface.

Redirect : A technique for making a web page available under more than one URL address. When a web browser attempts to open a URL that has been redirected, a page with a different URL is opened. Similarly, domain redirection or domain forwarding is when all pages in a URL domain are redirected to a different domain. URL redirection is done for various reasons: for URL shortening; to prevent broken links when web pages are moved; to allow multiple domain names belonging to the same owner to refer to a single website; to guide navigation into and out of a website; for privacy protection; and for hostile purposes such as phishing attacks or malware distribution. Redirects can be set up on the server and the client side. †

Redirect chain : Two or more redirects in succession. Search engine optimization (SEO) best practices suggest to avoid redirect chains, as each redirect is said to share less link equity.

Redundancy : The intentional duplication of critical components or functions of a system with the intention of increasing reliability of the system. There are four major forms of redundancy: hardware redundancy, such as dual modular redundancy and triple modular redundancy; information redundancy, such as error detection and correction methods; time redundancy, performing the same operation multiple times such as multiple executions of a program or multiple copies of data transmitted; and software redundancy such as N-version programming. † : The often unnoticed or unintentional duplication of software with the consequence of making the software less efficient and more difficult to maintain.

Redux : A JavaScript library for managing application state. It is most commonly used with libraries such as React or Angular for building user interfaces. Redux was created in 2015 by Dan Abramov and Andrew Clark. † ℹ︎ redux.js.org

Reed-Solomon codes : A group of error-correcting codes that were introduced in 1960 by Irving S. Reed and Gustave Solomon. They have many applications, the most prominent of which include consumer technologies such as MiniDiscs, CDs, DVDs, Blu-ray discs, QR codes, data transmission technologies such as DSL and WiMAX, broadcast systems such as satellite communications, DVB and ATSC, and storage systems such as RAID 6. Reed-Solomon codes operate on blocks of data treated as sets of finite-field elements called symbols, where they are able to detect and correct multiple symbol errors. For example, Reed-Solomon codes can help correct burst errors associated with media defects, and make data transmissions over erasure channels more reliable. †

Refactoring : The process of restructuring and optimizing existing computer code—changing the factoring—without changing its external behavior. Refactoring is intended to improve non-functional attributes of the software. Advantages include improved code readability and reduced complexity; these can improve source code maintainability and create a more expressive internal architecture or object model to improve extensibility. †

Reference error : As ReferenceError, an object representing an error (and the error itself) when a non-existent variable is referenced. ‡

Referential opacity : A property of computer programs, an expression that is not referentially transparent (and therefore referentially opaque). †

Referential transparency : A property of computer programs, an expression is called referentially transparent if it can be replaced with its corresponding value without changing the program’s behavior. This requires that the expression be pure, that is to say the expression value must be the same for the same inputs and its evaluation must have no side effects. †

Reflow : The re-processing and re-drawing a part or all of a web page after making changes DOM or CSS changes. Reflow affects the (perceived) performance of a page or app. ‡

Regex : → Regular expression

Registrar : A company that manages the reservation of Internet domain names. A domain name registrar must be accredited by and operate in accordance with the guidelines of a generic top-level domain (gTLD) registry or a country code top-level domain (ccTLD) registry. †

Regular expression : A sequence of characters that define a search pattern. Usually such patterns are used by string searching algorithms for “find” or “find and replace” operations on strings, or for input validation. Regular expressions are a technique developed in theoretical computer science and formal language theory. They are used in search engines, “search and replace” dialogs of word processors and text editors, in text processing utilities such as sed and awk, and in lexical analysis. Many programming languages provide regex capabilities either built-in or via libraries. †

Rehydration : → Hydration

Relational Data Stream Management System : A distributed, in-memory data stream management system (DSMS) that is designed to use standards-compliant SQL queries to process unstructured and structured data streams in real-time. Unlike SQL queries executed in a traditional RDBMS, which return a result and exit, SQL queries executed in a RDSMS do not exit, generating results continuously as new data become available. †

Relational database : A digital database based on the relational model of data. A relational database has gradually come to describe a broader class of database systems, which at a minimum present the data to the user as relations (a presentation in tabular form, i.e., as a collection of tables with each table consisting of a set of rows and columns), and provide relational operators to manipulate the data in tabular form. †

Relational Database Management System : A database management system (DBMS) based on the relational model. Most databases in widespread use today are based on this model. †

Relational model : An approach to database management using a structure and language consistent with first-order predicate logic, first described in 1969 by Edgar F. Codd, where all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database. The purpose of the relational model is to provide a declarative method for specifying data and queries: Users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries. †

Relative sizing : In CSS, the using of units relative to something else, like a parent element’s font size or width.

Relaunch : The (usually public) release of a significantly revised software product.

Rem : → Root em

Remote Authentication Dial-In User Service : A networking protocol that provides centralized authentication, authorization, and accounting (AAA) management for users who connect and use a network service. RADIUS was developed in 1991 by Livingston Enterprises as an access server authentication and accounting protocol. It was later brought into IEEE 802 and IETF standards. RADIUS is a client/server protocol that runs in the application layer, and can use either TCP or UDP. †

Remote Desktop Protocol : A proprietary protocol developed by Microsoft which provides a user with a graphical interface to connect to another computer over a network connection. The user employs RDP client software for this purpose, while the other computer must run RDP server software. The protocol is an extension of the ITU-T T.128 application sharing protocol. †

Remote method invocation : The calling of a method on a remote object, the object-oriented programming analog of a remote procedure call (RPC). †

Remote procedure call : The causing of a procedure (subroutine) to execute in a different address space (commonly on another computer on a shared network), with the call being coded as if it was a normal (local) procedure call. That is, without explicitly coding the details for the remote interaction, the programmer writes essentially the same code whether the subroutine is local to the executing program, or remote. †

Render tree : A tree of the visible elements of a page as generated from the DOM and CSSOM trees. Elements for metadata content and elements “hidden” through display: none are not part of the render tree.

Renderer : A user agent that interprets the semantics of style sheets and renders documents that use them.

Rendering : The transforming of HTML documents and other resources of a web page into an interactive visual representation in a web browser. †

Rendering engine : → Browser engine

RenderingNG : A substantially revised and updated architecture of the Blink rendering engine used by the Chromium project. ℹ︎ is.gd/Kx6lG0

REP : → Robots Exclusion Protocol

REPL : → Read-Eval-Print Loop

Replaceable Character Data : A term (“RCDATA”) used to declare that a markup element may contain text content and entity references, but not sub-elements.

Replaced element : An element whose representation is outside the scope of CSS; they are external objects whose representation is independent of the CSS formatting model. Put in simpler terms, they are elements whose contents are not affected by the current document’s styles. The position of the replaced element can be affected using CSS, but not the contents of the replaced element itself. Some replaced elements, such as iframe elements, may have style sheets of their own, but they do not inherit the styles of the parent document. Typical replaced elements include iframe, video, embed, and img. ‡

Replay attack : A form of network attack in which valid data transmission is maliciously or fraudulently repeated or delayed. This is carried out either by the originator or by an adversary who intercepts the data and re-transmits it, possibly as part of a spoofing attack by IP packet substitution. This is one of the lower-tier versions of a man-in-the-middle attack. Replay attacks are usually passive in nature. †

Repo : → Repository

Repository : A storage location for software. Repositories can be public or private, centralized or decentralized (as with version control repositories), and cover any kind of software.

Representational State Transfer : A group of software architecture design constraints that bring about efficient, reliable, and scalable distributed systems. A system is called RESTful when it adheres to those constraints. The basic idea of REST is that a resource, e.g., a document, is transferred with its state and relationships (hypertext) via well-defined, standardized operations and formats. Often APIs or services call themselves RESTful when they directly modify a type of document as opposed to triggering actions elsewhere. ‡

Request : In HTTP, a client’s message to a server soliciting a response. A request message consists of a request line (e.g., GET /images/logo.png HTTP/1.1, which requests a resource called /images/logo.png from the server), request header fields (e.g., Accept-Language: en), an empty line, and an optional message body. †

Request for Comments : A type of document from the technology community. An RFC document may come from many bodies including from the Internet Engineering Task Force (IETF), the Internet Research Task Force (IRTF), the Internet Architecture Board (IAB), or from independent authors. The RFC system is supported by the Internet Society (ISOC). An RFC is authored by engineers and computer scientists in the form of a memorandum describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems. It is submitted either for peer review or to convey new concepts, information, and occasionally engineering humor. The IETF adopts some of the proposals published as RFCs as Internet Standards. †

Request header : An HTTP header that can be used in an HTTP request, and that does not relate to the content of the message. Request headers, like Accept, Accept-*, or If-*, allow to perform conditional requests; others like Cookie, User-Agent, or Referer narrow down the context so that the server can tailor the answer. Not all headers appearing in a request are request headers. For example, the Content-Length appearing in a POST request is actually an entity header referring to the size of the body of the request message. However, these entity headers are often called request headers in such a context. ‡

Request method : → HTTP method

Requests per second : A common measure of the amount of traffic an information retrieval system, such as a search engine or a database, receives during one second. High-traffic systems must watch their RPS (or QPS, queries per second) in order to know when to scale the system to handle more load. †

RequireJS : A JavaScript file and module loader. ℹ︎ requirejs.org

Reset : → Reset style sheet

Reset style sheet : A set of CSS rules used to “clear” the formatting of HTML elements, or to make the respective formatting consistent in major web browsers. The usefulness of reset style sheets is disputed because they do not technically “reset” styling, and because in practice, their use is often unnecessary, only increasing the payload of the respective site or app.

Resolution : → Display resolution

Resource Description Framework : A family of W3C specifications originally designed as a metadata data model. RDF has come to be used as a general method for conceptual description or modeling of information that is implemented in web resources, using a variety of syntax notations and data serialization formats. It is also used in knowledge management applications. RDF became a W3C Recommendation in 1999. † ℹ︎ w3.org/TR/rdf11-concepts

Resource Hints : A number of HTML link relationships that allow to indicate what resources to fetch ahead of time in order to improve performance. Resource Hints include dns-prefetch, preconnect, prefetch, and prerender, and can be implemented using the HTML link element as well as the Link HTTP header. ℹ︎ w3.org/TR/resource-hints

Resource record : A DNS record type. Each resource record has a type (name and number), an expiration time (time to live), a class, and type-specific data. Resource records of the same type are described as a resource record set (RRset), having no special ordering. DNS resolvers return the entire set upon query, but servers may implement round-robin ordering to achieve load balancing. †

Response : In HTTP, a server’s answer to a client. A response message consists of a status line which includes the status code and reason message (e.g., HTTP/1.1 200 OK, which indicates that the client’s request succeeded), response header fields (e.g., Content-Type: text/html), an empty line, and an optional message body. †

Response header : An HTTP header that can be used in an HTTP response and that does not relate to the content of the message. Response headers, like Age, Location, or Server are used to give a more detailed context of the response. Not all headers appearing in a response are response headers. For example, the Content-Length header is an entity header referring to the size of the body of the response message. However, these entity requests are usually called responses headers in such a context. ‡

Responsibility Assignment Matrix : A description of the participation of various roles in completing tasks or deliverables for a project or business process. When referred to as a RACI matrix, “RACI” stands for the four key responsibilities most typically used: responsible, accountable, consulted, and informed. RAMs and RACIs are used for defining and clarifying roles and responsibilities in cross-functional or departmental projects and processes. †

Responsive design : → Responsive web design

Responsive Images Community Group : A group of developers working towards “a client-side solution for delivering alternate image data based on device capabilities to prevent wasted bandwidth and optimize display for both screen and print.” The RICG was founded in 2012. ℹ︎ responsiveimages.org

Responsive web design : An approach to web design that makes web pages render well on a variety of devices and window or screen sizes. Recent work also considers the viewer proximity as part of the viewing context as an extension for responsive web design. Content, design, and performance are necessary across all devices to ensure usability and satisfaction. A site designed responsively adapts the layout to the viewing environment by using fluid, proportion-based grids, flexible images, and CSS media queries. Responsive web design has become more important as the amount of mobile traffic accounts for more than half of total Internet traffic. †

Responsiveness : → Responsive web design

REST : → Representational State Transfer

Restricted production : A statement like break or continue that, when followed by a line terminator, triggers the automatic insertion of a semicolon (ASI).

Revalidation : Cache behavior in which a cache checks with the origin of a resource whether the resource has changed. If it has (HTTP 200 “OK” response), the origin server will also send the updated resource; if has not (HTTP 304 “Not Modified”), the cache will keep the resource.

Reverse proxy : A reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers. These resources are then returned to the client, appearing as if they originated from the reverse proxy server itself. Popular web servers often use reverse-proxying functionality to shield application frameworks of weaker HTTP capabilities, where “weaker” means limitations to handle excessive load or a great variety of request formats. †

Revision control : → Version control

Revision Control System : → Version control

RFC : → Request for Comments

RGB : → Red, Green, and Blue

RIA : → Rich Internet Application

RIB : → Routing Information Base

RICG : → Responsive Images Community Group

Rich Internet Application : → Rich Web Application

Rich Site Summary : → RDF Site Summary

Rich Text Format : A proprietary document file format with published specification developed by Microsoft from 1987 until 2008 for cross-platform document interchange with Microsoft products. Prior to 2008, Microsoft published updated specifications for RTF with major revisions of Microsoft Word and Office versions. Most word processors are able to read and write some versions of RTF. There are several different revisions of RTF specification and portability of files depends on what version of RTF is being used. †

Rich Web Application : A web application that has many of the characteristics of desktop application software. The concept is closely related to a single-page application, and may allow the user interactive features such as drag and drop, context menus, WYSIWYG editing, etc. Prior to HTML 5, approaches to RWAs were based on Adobe Flash, Java applets, JavaFX, or Microsoft Silverlight. †

Right-to-left : A script in which writing starts from the right of a page and continues to the left. Arabic, Hebrew, Persian, Urdu, and Sindhi are the most widespread RTL writing systems in modern times. †

Rijndael : → Advanced Encryption Standard

RIRO : → Rubbish In, Rubbish Out

RMI : → Remote method invocation

Roadmap : A flexible planning technique to support strategic and long-range planning, by matching short-term and long-term goals with specific technology solutions. A roadmap is a plan that applies to a new product or process and may include using technology forecasting or scouting to identify suitable emerging technologies. †

Robot : → Crawler

Robots Exclusion Protocol : A combination of standards and conventions governing web crawler behavior and search engine indexing. The REP includes the robots exclusion standard (robots.txt), crawling and indexing directives for HTML meta elements, the Sitemaps protocol, and the rel=nofollow microformat.

Robots exclusion standard : → robots.txt

robots.txt : A standard and special file used by websites to communicate with web robots and crawlers. The standard specifies how to inform the web robot about which areas of the website should not be processed or scanned. Robots are often used by search engines to categorize websites. Not all robots cooperate with the standard; email harvesters, spambots, malware, and robots that scan for security vulnerabilities may even start with the portions of the website where they have been told to stay out. † ℹ︎ robotstxt.org

Robustness Principle : → Postel’s Law

Root : → Root directory : → Root element : → Root node : → Superuser

Root directory : The first or top-most directory in a hierarchy in a computer file system. It can be likened to the trunk of a tree, as the starting point where all branches originate from. The root file system is the file system contained on the same disk partition on which the root directory is located; it is the file system on top of which all other file systems are mounted as the system boots up. †

Root element : The element that encloses all other elements in a document and is therefore the sole parent element to all other elements. A root element is also the root node of the DOM. Root elements are also called document elements. In HTML documents, the html element is the root element. †

Root em : A typographic unit in CSS (rem) that corresponds with the computed value of the font size of the root element (for HTML, the html element).

Root name server : → Root server

Root node : The top-most node in a tree. The root node has no parent. It is the node at which algorithms on the tree begin, since a tree being a data structure, one can only pass from parents to children. †

Root server : A name server for the root zone of the Domain Name System (DNS) of the Internet. It directly answers requests for records in the root zone and answers other requests by returning a list of the authoritative name servers for the appropriate top-level domain (TLD). Root name servers are a critical part of the Internet infrastructure because they are the first step in translating (resolving) human-readable host names into IP addresses that are used in communication between Internet hosts. †

Root zone : The top-level DNS zone in the hierarchical namespace of the Domain Name System (DNS) of the Internet. Since 2016, the root zone has been overseen by the Internet Corporation for Assigned Names and Numbers (ICANN), which delegates the management to a subsidiary acting as the Internet Assigned Numbers Authority (IANA). Distribution services are provided by Verisign. †

Rooting : The process of allowing users of smartphones, tablets, and other devices running the Android mobile operating system to attain privileged control (known as root access) over various subsystems. As Android uses the Linux kernel, rooting an Android device gives similar access to administrative (superuser) permissions as on Linux or any other Unix-like operating system. †

Round-Trip Delay Time : → Round-Trip Time

Round-Trip Time : The length of time it takes for a signal to be sent plus the length of time it takes for an acknowledgement of that signal to be received. This time delay includes the propagation times for the paths between the two communication endpoints. In the context of computer networks, the signal is generally a data packet, and the RTT is also known as the ping time. An Internet user can determine the RTT by using the ping command. †

Route 53 : A Domain Name System (DNS) service. Released in 2010, Route 53 is part of Amazon.com’s cloud computing platform, Amazon Web Services (AWS). The name is a possible reference to U.S. Routes, and “53” is a reference to the TCP/UDP port 53, where DNS server requests are addressed. In addition to being able to route users to various AWS services, including Elastic Compute Cloud (EC2) instances, Route 53 also enables AWS customers to route users to non-AWS infrastructure and to monitor the health of their application and its endpoints. † ℹ︎ aws.amazon.com/route53

Router : For applications, a library that decides what web page is presented by a given URL. This middleware module is used for all URL functions, as these are given a path to a file that is rendered subsequently. ‡ : For networks, a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Data sent through the Internet, such as a web page or email, is in the form of data packets. A packet is typically forwarded from one router to another router through the networks that constitute an inter-network (e.g., the Internet) until it reaches its destination node. †

Routine : A sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. †

Routing : The process of selecting a path for traffic in a network or between or across multiple networks. The routing process usually directs forwarding on the basis of routing tables. †

Routing Information Base : → Routing table

Routing table : A data table stored in a router or a network host that lists the routes to particular network destinations, and in some cases, metrics (distances) associated with those routes. The routing table contains information about the topology of the network immediately around it. †

RPC : → Remote procedure call

RPM : → RPM Package Manager

RPM Package Manager : A package management system originally called Red Hat Package Manager. The name “RPM” refers to .rpm file format and the package manager program itself. RPM was intended primarily for Linux distributions; the file format is the baseline package format of the Linux Standard Base. It was first released in 1997. † ℹ︎ rpm.org

RPO : → Recovery Point Objective

RPS : → Requests per second

RR : → Resource record

RSS : → RDF Site Summary : → Really Simple Syndication : → Rich Site Summary

RTD : → Round-Trip Delay Time

RTF : → Rich Text Format

RTFM : → Read the Fucking Manual

RTL : → Right-to-left

RTO : → Recovery Time Objective

RTT : → Round-Trip Time

Rubber ducking : A method of debugging code. The name is a reference to a story in the book The Pragmatic Programmer in which a programmer would carry around a rubber duck and debug their code by forcing themselves to explain it, line-by-line, to the duck. Many other terms exist for this technique, often involving inanimate objects. †

Rubbish In, Rubbish Out : → Garbage In, Garbage Out

Ruby : As a programming language, an interpreted, high-level, general-purpose language. Ruby is dynamically typed and uses garbage collection. It supports multiple programming paradigms, including procedural, object-oriented, and functional programming. Ruby was designed and developed in the 1990s by Yukihiro Matsumoto. According to the creator, Ruby was influenced by Perl, Smalltalk, Eiffel, Ada, Basic, and Lisp. † ℹ︎ ruby-lang.org : As markup, special HTML elements for brief text that goes alongside a base text; such Ruby text is used for pronunciation and annotation in East Asian documents. ℹ︎ w3.org/TR/ruby

Ruby on Rails : A server-side web application framework written in Ruby. Rails is a model-view-controller (MVC) framework, providing default structures for a database, a web service, and web pages. It encourages and facilitates the use of web standards such as JSON or XML for data transfer, HTML, CSS, and JavaScript for user interfacing. In addition to MVC, Rails emphasizes the use of other well-known software engineering patterns and paradigms, including Convention over Configuration (CoC) and Don’t Repeat Yourself (DRY). Rails was first released in 2005. † ℹ︎ rubyonrails.org

Rule : A CSS selector and its successive declaration block.

Rule set : → Rule

RUM : → Real User Monitoring

Runbook : A compilation of routine procedures and operations that a system administrator or operator carries out. System administrators in IT departments and network operations centers (NOCs) use runbooks as a reference. Typically, a runbook contains procedures to begin, stop, supervise, and debug a system. It may also describe procedures for handling special requests and contingencies. An effective runbook allows other operators, with prerequisite expertise, to effectively manage and troubleshoot a system. †

Runtime compilation : → Just-in-time compilation

RWD : → Responsive web design

RxJS : → Reactive Extensions for JavaScript

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