f.md

F

FaaS : → Function as a Service

Facade pattern : A software design pattern commonly used in object-oriented programming. Analogous to a facade in architecture, a facade is an object that serves as a front-facing interface masking more complex underlying or structural code. A facade can improve the readability and usability of a software library by masking interaction with more complex components behind a single (and often simplified) API; provide a context-specific interface to more generic functionality (complete with context-specific input validation); and serve as a launching point for a broader refactor of monolithic or tightly-coupled systems in favor of more loosely-coupled code. †

Fagan inspection : A process of trying to find defects in documents (such as source code or formal specifications) during various phases of the software development process. It defines a process as an activity with pre-specified entry and exit criteria. Fagan inspection is named after Michael Fagan, who is credited as being the inventor of formal software inspections. †

Fagan testing : → Fagan inspection

Failover : The switching to a redundant or standby computer server, system, hardware component, or network upon the failure or abnormal termination of the previously active application, server, system, hardware component, or network. Failover and switchover are essentially the same operation, except that failover is automatic and usually operates without warning, while switchover requires human intervention. †

Fallback : A contingency option to be taken if the preferred choice is unavailable. †

False negative : An error in which a test result improperly indicates no presence of a condition, such as a disease (the result is negative), when in reality it is present. A false negative is also known as a type II error. †

False positive : An error in data reporting in which a test result improperly indicates presence of a condition (the result is positive), when in reality it is not present. A false positive is also known as a type I error. †

Falsy : A value that is considered false when encountered in a Boolean context, which is relevant notably with JavaScript which uses type conversion to coerce any value to a Boolean in contexts that require it, such as conditionals and loops. ‡

Fat footer : A footer UI element but with a substantial amount of content and links. A “fat footer” stands in contrast to a minimal web page footer consisting only of basic navigation aids (like a home link) and meta-information (like a legal notice and contact information).

Favelet : → Bookmarklet

Favicon : A file containing one or more small icons, associated with a particular website or web page. Browsers that provide favicon support typically display a page’s favicon in the browser’s address bar (sometimes in the history as well) and next to the page’s name in a list of bookmarks. Browsers that support a tabbed document interface typically show a page’s favicon next to the page’s title on the tab, and site-specific browsers use the favicon as a desktop icon. †

Favorite : → Bookmark

FCP : → First Contentful Paint

Feature creep : The excessive ongoing expansion or addition of new features in a product, especially in computer software, video games, and consumer and business electronics. These extra features go beyond the basic function of the product and can result in software bloat and over-complication rather than simple design. †

Feature detection : A technique for handling differences between runtime environments (typically web browsers or user agents), by programmatically testing for clues that the environment may or may not offer certain functionality. This information is then used to make the application adapt in some way to suit the environment, for example to make use of certain APIs or to tailor the user experience. Feature detection is said to be more reliable and future-proof than other techniques, like browser sniffing and browser-specific CSS hacks. †

Feature phone : A mobile phone that retains the form factor of earlier-generation phones, with button-based input and a small display. Feature phones are sometimes called dumbphones in contrast with touch-input smartphones. Feature phones tend to use an embedded operating system with a small and simple graphical user interface, unlike large and complex general-purpose mobile operating systems like Android or iOS. Feature phones typically provide voice calling and text messaging functionality as well as basic multimedia and Internet capabilities and other services offered by the user’s wireless service provider. †

Feature testing : → Feature detection

Federal Information Processing Standard : A publicly announced standard developed by the National Institute of Standards and Technology (NIST) for use in computer systems by non-military American government agencies and government contractors. FIPS standards are issued to establish requirements for purposes such as ensuring computer security and interoperability, and are intended for cases in which suitable industry standards do not already exist. Many FIPS specifications are modified versions of standards used in the technical communities, such as the American National Standards Institute (ANSI), the Institute of Electrical and Electronics Engineers (IEEE), and the International Organization for Standardization (ISO). † ℹ︎ is.gd/Obox4z

Federated Learning of Cohorts : A type of web tracking through federated learning. FLoC groups people into “cohorts” based on their browsing history for the purpose of interest-based advertising. Google began testing the technology in the Chrome browser in March 2021 as a replacement for third-party cookies; in July 2021, Google quietly suspended development. † ℹ︎ github.com/WICG/floc

Federation : A group of computing or network providers agreeing upon standards of operation in a collective fashion. The term may be used when describing the interoperation of distinct, formally disconnected, telecommunications networks that may have different internal structures; “federation” may also be referred to when groups attempt to delegate collective authority of development, in order to prevent fragmentation. †

Feed : A data format used for providing users with frequently updated content. Content distributors syndicate a web feed, thereby allowing users to subscribe to a channel by adding the feed resource address to a news aggregator client (also called a feed reader or a news reader). Users typically subscribe to a feed by manually entering the URL of a feed, clicking a link in a web browser, or by dragging the link from the web browser to the aggregator. The kinds of content delivered by a web feed are usually HTML (web page content) or links to web pages and digital media. Common feed formats are RSS, Atom, and JSON Feed. †

Feed reader : → News aggregator

Fetch API : An interface for fetching resources across a network. The Fetch API is comparable to XMLHttpRequest, but provides a more powerful and flexible feature set building on a generic definition of Request and Response objects. ‡ ℹ︎ fetch.spec.whatwg.org

FID : → First Input Delay

FIFO : → First In, First Out

Figma : A primarily web-based vector graphics editor and prototyping tool, with additional features enabled by desktop applications for macOS and Windows. The Figma Mirror companion apps for Android and iOS allow viewing Figma prototypes in real-time on mobile devices. The feature set of Figma focuses on use in user interface and user experience design, with an emphasis on real-time collaboration. Figma was released in 2016. † ℹ︎ figma.com

File : A computer resource for recording data discretely in a computer storage device. Just as words can be written to paper, so can information be written to a computer file. †

File locking : A mechanism that restricts access to a computer file by allowing only one user or process to access it in a specific time. Systems implement locking to prevent the classic interceding update scenario, which is a typical example of a race condition, by enforcing the serialization of update processes to any given file. †

File manager : A computer program that provides a user interface to manage files and folders. The most common operations performed on files or groups of files include creating, opening (e.g., viewing, playing, editing, or printing), renaming, moving or copying, deleting and searching for files, as well as modifying file attributes, properties, and file permissions. †

File system : A software that controls how data is stored and retrieved. Without a file system, data placed in a storage medium would be one large body of data with no way to tell where one piece of data stops and the next begins. Taking its name from the way paper-based data management system is named, each group of data is called a file. There are many different kinds of file systems. Each one has different structure and logic, properties of speed, flexibility, security, or size. †

File Transfer Protocol : A standard network protocol used for the transfer of computer files between a client and server on a computer network. FTP is built on a client-server model architecture using separate control and data connections between the client and the server. FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. FTP was not designed to be a secure protocol, and has many security weaknesses. †

Fingerprinting : In computing in general, a procedure that maps an arbitrarily large data item (such as a computer file) to a much shorter bit string, its fingerprint, that uniquely identifies the original data for all practical purposes just as human fingerprints uniquely identify people. This fingerprint may be used for data de-duplication purposes. This kind of fingerprinting is also referred to as file fingerprinting, data fingerprinting, or structured data fingerprinting. † : In computer security, information collected about a remote computing device for the purpose of identification. Fingerprints can be used to fully or partially identify individual users or devices even when persistent cookies (and zombie cookies) cannot be read or stored in the browser, the client IP address is hidden, and even if one switches to another browser on the same device. This may allow a remote application to detect and prevent online identity theft and credit card fraud, but also to compile long-term records of individuals’ browsing histories even when they are attempting to avoid tracking. †

FIPS : → Federal Information Processing Standard

Firebird : → Firefox

Firefox : A cross-platform web browser. Firefox was developed by the Mozilla Foundation and its subsidiary, Mozilla Corporation, and first released in 2002, named “Phoenix.” From 2003 to 2004, Phoenix was called “Firebird” before being renamed to “Firefox.” ℹ︎ mozilla.org/firefox

First Contentful Paint : The time when the browser renders the first bit of content from the DOM, providing the first feedback to the user that the page is loading. The question “Is it happening?” is “yes” when the first contentful paint completes. ‡

First CPU Idle : The time when a page is minimally interactive, or when the window is quiet enough to handle user input. It is a non-standard Google web performance metric. Generally, it occurs when most, but not necessarily all visible UI elements are interactive, and the user interface responds, on average, to most user input within 50 ms. ‡

First In, First Out : A method for organizing and manipulating a data buffer, where the oldest (first) entry, or “head” of the queue, is processed first. It is analogous to processing a queue with first-come, first-served (FCFS) behavior, where the people leave the queue in the order in which they arrive. †

First Input Delay : The time from when a user first interacts with a site (i.e., when they click a link, tap on a button, or use a custom, JavaScript-powered control) to the time when the browser is able to respond to that interaction. It is the length of time, in milliseconds, between the first user interaction on a web page and the browser’s response to that interaction. Scrolling and zooming are not included in this metric. ‡

First Interactive : → First CPU Idle

First Meaningful Paint : The paint after which the biggest above-the-fold layout change has happened and web fonts have loaded. It is when the answer to “Is it useful?” becomes “yes,” that is, upon first meaningful paint completion. ‡

First Paint : The time between navigation and when the browser renders the first pixels to the screen, rendering anything that is visually different from what was on the screen prior to navigation. It answers the question “Is it happening?” ‡

First Public Working Draft : The first official version of a World Wide Web Consortium (W3C) Working Draft.

First-class function : A function that is treated like any other variable in the respective language. ‡

First-order function : → First-class function

Fitts’s Law : A predictive model of human movement primarily used in human-computer interaction and ergonomics. This scientific law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target. Fitts’s Law is used to model the act of pointing, either by physically touching an object with a hand or finger, or virtually, by pointing to an object on a computer monitor using a pointing device. Fitts’s Law has been shown to apply under a variety of conditions. †

Fixed : A CSS positioning scheme in which an element behaves as if it was set to absolute positioning, yet its containing block is the viewport. : A web design approach in which page elements have a fixed as opposed to a variable width. Outdated with the popularity of mobile devices and the concept of responsive design.

Flame graph : A flame-like visualization method for software profiling. ℹ︎ is.gd/EnyPjs

Flash : A deprecated multimedia software platform used for the production of animations, games, and applications. Flash was first released in 1993 (SmartSketch), rebranded in 1995 (FutureSplash Animator) and, after being bought by Macromedia, again renamed in 1996 (Macromedia Flash). Although Flash was previously a dominant platform for online multimedia content, it has been abandoned as Adobe, who purchased Macromedia in 2005, favored a transition to HTML. †

Flash of Faux Text : The effect when a browser switches from a fallback font to a particular web font before loading and applying yet other fonts.

Flash of Invisible Text : The effect when a browser hides text until the respective web font is loaded, possibly leading to invisible content.

Flash of Unstyled Content : → Flash of Unstyled Text

Flash of Unstyled Text : The effect when a web page appears briefly with the browser’s default styles prior to loading an external style sheet, due to the web browser engine rendering the page before all information is retrieved. The page corrects itself as soon as the style rules are loaded and applied; however, the shift may be distracting. †

Flash Player : A software for using content created on the Adobe Flash platform, including viewing multimedia contents, executing rich Internet applications, and streaming audio and video. Flash Player can run from a web browser as a browser plugin or on supported mobile devices. It was created by Macromedia and has been developed and distributed by Adobe since Adobe acquired Macromedia in 2005. Support for Flash Player ended at the end of 2020. †

Flat Design : A minimalist design language and style that emphasizes the use of simple elements and typography as well as flat colors. The emergence and popularization of the International Typographic Style (Swiss Style) during the 1950s and 1960s is regarded as the starting point of Flat Design. †

Flex : A new value (flex) added to the CSS display property. Along with inline-flex it causes the element that it applies to to become a flex container, and the element’s children to each become a flex item. The items then participate in flex layout, and all of the properties defined in the CSS Flexible Box Layout Module may be applied. ‡ : → Flexbox

Flexbox : A CSS web layout model for displaying items in a single dimension, as a row or as a column. In the specification for the CSS Flexible Box Layout Module, Flexbox is described as a layout model for user interface design. The key feature of Flexbox is that items in a flex layout can grow and shrink. Space can be assigned to the items themselves, or distributed between or around the items. Flexbox also enables alignment of items on the main or cross axis, thus providing a high level of control over the size and alignment of a group of items. ‡ ℹ︎ w3.org/TR/css-flexbox-1

Float : A single precision, 32-bit floating-point data type. : A mechanism for visual formatting in CSS building on the float property, allowing content to flow along an element’s sides.

FLoC : → Federated Learning of Cohorts

Flock : A discontinued web browser that specialized in providing social networking and Web 2.0 facilities built into its user interface. Flock was released in 2005 and discontinued in 2011. †

FLOSS : → Free/Libre and Open Source Software

Flow content : An HTML content type that includes most HTML elements.

Flow of control : → Control flow

Fluent Design System : A design language developed in 2017 by Microsoft. Fluent Design is a revamp of Microsoft Design Language 2 that includes guidelines for the designs and interactions used within software designed for all Windows 10 devices and platforms. The system is based on five key components: Light, Depth, Motion, Material, and Scale. The new design language includes more prominent use of motion, depth, and translucency effects. †

Fluid : → Liquid

FMP : → First Meaningful Paint

FOAF : → Friend of a Friend

FOFT : → Flash of Faux Text

Fold : The imaginary separator between the visible and the invisible part of a web page.

FOIT : → Flash of Invisible Text

Folksonomy : The system in which users apply public tags to online items, typically to make those items easier for themselves or others to find later. Over time, this can give rise to a classification system based on those tags and how often they are applied or searched for, in contrast to a taxonomic classification designed by the owners of the content and specified when it is published. Folksonomies are also known as collaborative tagging, social classification, social indexing, and social tagging. †

Font : With the advent of digital typography, “font” is frequently synonymous with “typeface.” Each style is in a separate font file—for instance, the typeface Bulmer may include the fonts “Bulmer Roman,” “Bulmer,” “Bulmer Bold,” and “Bulmer Extended,” but the term “font” might be applied either to one of these alone or to the whole typeface. In both traditional typesetting and modern usage, “font” also refers to the delivery mechanism of the typeface design. In traditional typesetting, a font would be made from metal or wood. Today, a font is a digital file. †

Font Awesome : An icon toolkit based on CSS. Font Awesome was first released in 2012. ℹ︎ fontawesome.com

Font block period : A part of the font display timeline that governs that if a particular font face is not loaded, any element attempting to use it must render an invisible fallback font face. If the font face successfully loads during this period, it is used normally. ‡

Font failure period : A part of the font display timeline that governs that if a particular font face is not loaded, the user agent treats it as a failed load causing normal font fallback. ‡

Font subsetting : The use of only the glyphs and features needed from a given font.

Font swap period : A part of the font display timeline that governs that if a particular font face is not loaded, any element attempting to use it must render a fallback font face. If the font face successfully loads during this period, it is used normally. ‡

Foobar : Meta-syntactic variables and placeholder names (“foobar”, “foo”, “bar”, etc.) used in computer programming and documentation when a concept is to be demonstrated and the respective variable’s, function’s, or command’s exact identity is unimportant. †

for : → Loop

foreach : → Loop

Foreign key : A set of attributes in a database table that refers to the primary key of another table. The foreign key links these two tables. †

Fork : The taking of a copy of source code from one software package and starting independent development on it, creating a distinct and separate piece of software. A fork can imply not merely a development branch, but also a split in the developer community, a form of schism. †

Form : An interface that allows to enter data that is sent to a server for processing. Forms can resemble paper or database forms because web users fill out the forms using checkboxes, radio buttons, or text fields. In HTML, forms are set up using the form and related elements. †

Formatting context : A concept that governs how boxes are laid out with CSS. There are different formatting contexts, like block formatting context, inline formatting context, and table formatting context.

Formatting Output Specification Instance : A style sheet language for SGML and, later, XML. FOSI was developed in the 1990s by the U.S. Department of Defense to control the pagination and layout of SGML and XML technical data. FOSI style sheets are themselves written in SGML, an approach that would later be adopted by XSL. †

Forward compatibility : A design characteristic that allows a system to accept input intended for a later version of itself. The concept can be applied to entire systems, telecommunication signals, electrical interfaces, data communication protocols, file formats, and programming languages. A standard supports forward compatibility if a product that complies with earlier versions can “gracefully” process input designed for later versions of the standard, ignoring new parts which it does not understand. †

Forward proxy : → Proxy server

Forward secrecy : A feature of specific key agreement protocols that gives assurances that session keys will not be compromised even if long-term secrets used in the session key exchange are compromised. For HTTPS, the long-term secret is typically the private signing key of the server. The value of forward secrecy is that it protects past communication, yet it also depends on the capabilities of the adversary. †

FOSI : → Formatting Output Specification Instance

FOSS : → Free and Open Source Software

FOUC : → Flash of Unstyled Content

FOUT : → Flash of Unstyled Text

FPS : → Frames per second

FPWD : → First Public Working Draft

FQDN : → Fully qualified domain name

Fragment identifier : A string of characters that refers to a resource that is subordinate to another, primary resource. The primary resource is identified by a Uniform Resource Identifier (URI), and the fragment identifier points to the subordinate resource. The fragment identifier introduced by a hash mark (#) is the optional last part of a URL for a document. It is typically used to identify a portion of that document. The hash mark separator is not part of the fragment identifier. †

Frame : A part of a web page or browser window which displays content independent of its container, with the ability to load content independently. The HTML or media elements shown in a frame may come from a different website as the other elements of content on display, although this practice, known as framing, is today often regarded as a violation of same-origin policy and has been considered a form of copyright infringement. †

Frame busting : → Framekiller

Frame rate : The frequency (rate) at which consecutive images called frames appear on a display. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be called the frame frequency, and be expressed in Hertz. †

Framekiller : A technique used by websites and applications to prevent their web pages from being displayed within a frame, to avoid being displayed without permission or for malicious purposes, like as part of a clickjacking attack. †

Frames per second : → Frame rate

Framework : → HTML/CSS framework : → JavaScript framework : → Software framework : → Web framework

Frameset : A group of named frames which can point to web pages or media. †

Free and Open Source Software : Software that can be classified as both free software and open source software, that is, anyone is freely licensed to use, copy, study, and change the software in any way, and the source code is openly shared so that people are encouraged to voluntarily improve the design of the software. This is in contrast to proprietary software, where the software is under restrictive copyright licensing and the source code is usually hidden from the users. †

Free Software Foundation : A non-profit organization that supports the free software movement and which promotes the universal freedom to study, distribute, create, and modify computer software, with the organization’s preference for software being distributed under copyleft (“share alike”) terms. The FSF was founded in 1985 by Richard Stallman. † ℹ︎ fsf.org

Free variable : A notation (symbol) that specifies places in an expression where substitution may take place and is not a parameter of this or any container expression. Some older books use the terms real variable and apparent variable for free variable and bound variable, respectively. The idea is related to a placeholder (a symbol that will later be replaced by some literal string), or a wildcard character that stands for an unspecified symbol. †

Friend of a Friend : A machine-readable ontology describing persons, their activities, and their relations to other people and objects. Anyone can use FOAF to describe themselves. FOAF allows groups of people to describe social networks without the need for a centralized database. FOAF is a descriptive vocabulary expressed using the Resource Description Framework (RDF) and the Web Ontology Language (OWL). † ℹ︎ foaf-project.org

Frontend : The presentation layer of a piece of software, usually an abstraction that simplifies the underlying component by providing a user-friendly interface. In the client-server model, the client is considered the front end, even when some presentation work is done on the server itself. †

FrontPage : A discontinued WYSIWYG HTML editor and website administration tool from Microsoft for the Microsoft Windows line of operating systems. It was branded as part of the Microsoft Office suite from 1997 to 2003. Microsoft FrontPage has since been replaced by Microsoft Expression Web and SharePoint Designer, which were first released in 2006 alongside Microsoft Office 2007, but these two products were also discontinued. †

fs : → File system

FS : → Forward secrecy

FSF : → Free Software Foundation

FTP : → File Transfer Protocol

FTP over SSH : The practice of tunneling a normal FTP session over a Secure Shell connection. †

FTP Secure : → FTPS

FTP-SSL : → FTPS

FTPS : An extension to the commonly used File Transfer Protocol (FTP) that adds support for the Transport Layer Security (TLS) and, formerly, the Secure Sockets Layer (SSL, which is now prohibited by RFC 7568) cryptographic protocols. FTPS should not be confused with the SSH File Transfer Protocol (SFTP), a secure file transfer subsystem for the Secure Shell (SSH) protocol with which it is not compatible; it is also different from FTP over SSH. †

Fugu : A Google project designed to close the capabilities gap between web and native apps. Fugu provides or aims to provide APIs that allow web apps to, for example, share information (Web Share API), pick contacts (Contact Picker API), or process OTP messages (SMS Receiver API). ℹ︎ is.gd/Yyn0oQ

Full Service : A web agency term for the ability to provide all the services for an entire product lifecycle, like website conception, design, development, maintenance, and optimization.

Full Stack : → Solution stack

Full stack developer : A developer who can handle all aspects of website or app development, that is, including both frontend and backend development. : A developer who masters a particular solution stack.

Fully qualified domain name : A domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS). A fully qualified domain name specifies all domain levels, including the top-level domain and the root zone. A fully qualified domain name is distinguished by its lack of ambiguity, because it can be interpreted only in one way. It usually consists of a hostname and at least one higher-level domain (label) separated by the symbol “.”, and always ends in the top-level domain. †

Function : A code snippet that can be called by other code or by itself, or a variable that refers to the function. When a function is called, arguments are passed to the function as input, and the function can optionally return a value. A function in JavaScript is also an object. A function name is an identifier included as part of a function declaration or function expression. The function name’s scope depends on whether the function name is a declaration or expression. ‡

Function as a Service : A category of cloud computing services that provides a platform allowing customers to develop, run, and manage application functionalities without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app. Building an application following this model is one way of achieving a “serverless” architecture, and is typically used when building microservices applications. AWS Lambda was the first FaaS offering by a large public cloud vendor. †

Function binding : The creation of a new function using the bind() method.

function* : → Generator function

Functional programming : A programming paradigm that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data. Functional programming is a declarative programming paradigm in that programming is done with expressions or declarations instead of statements. In functional code, the output value of a function depends only on its arguments, so calling a function with the same value for an argument always produces the same result. This is in contrast to imperative programming where, in addition to a function’s arguments, global program state can affect a function’s resulting value. One of the key motivations for functional programming is making a program easier to understand by eliminating changes in state that do not depend on function inputs, so-called side effects. †

Functional testing : A quality assurance (QA) process and a type of black-box testing that bases its test cases on the specifications of the software component under test. Functions are tested by feeding them input and examining the output, and internal program structure is rarely considered (unlike white-box testing). Functional testing is conducted to evaluate the compliance of a system or component with specified functional requirements. Functional testing usually describes what a system does. †

FutureSplash : → Flash

Fuzz testing : → Fuzzing

Fuzzing : An automated software testing technique that involves providing invalid, unexpected, or random data as inputs to a computer program. The program is then monitored for exceptions such as crashes, failed code assertions, or memory leaks. †

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