l.md

L

L10N : → Localization

Lambda abstraction : → Anonymous function

Lambda expression : → Anonymous function

LAMP : → Linux, Apache, MySQL, PHP/Perl/Python

LAN : → Local area network

Landing page : A single web page that appears in response to clicking on an search-optimized search result, online advertisement, or marketing promotion. The landing page will usually display directed sales copy that is a logical extension of the advertisement, search result, or link. Landing pages are used for lead generation. The actions that a visitor takes on a landing page is what determines an advertiser’s conversion rate. A landing page may be part of a microsite or a single page within an organization’s main website. †

Language : → Markup language : → Programming language

Laravel : A PHP web framework based on Symfony, intended for the development of web applications following the model-view-controller (MVC) architectural pattern. Laravel features include a modular packaging system with a dedicated dependency manager, different ways for accessing relational databases, utilities that aid in application deployment and maintenance, and an orientation toward syntactic sugar. Laravel was released in 2011 by Taylor Otwell. † ℹ︎ laravel.com

Large-Scale Scrum : A product development framework that extends Scrum with scaling rules and guidelines without losing the original purposes of Scrum. There are two levels to the framework: The first LeSS level is designed for up to eight teams; the second level, known as “LeSS Huge,” introduces additional scaling elements for development with up to hundreds of developers. †

Largest Contentful Paint : The time it takes for the largest content element visible in the viewport to render. Large elements considered for measurement include images, videos, and large text blocks. ℹ︎ wicg.github.io/largest-contentful-paint

Last Call Working Draft : A mature version of a World Wide Web Consortium (W3C) Working Draft in need of test and implementation feedback.

Last In, First Out : → Stack

Latency : A time interval between the stimulation and response, or, from a more general point of view, a time delay between the cause and the effect of some physical change in the system being observed. Latency is physically a consequence of the limited velocity with which any physical interaction can propagate. The magnitude of this velocity is always less than or equal to the speed of light. Therefore, every physical system with any physical separation (distance) between cause and effect will experience some sort of latency, regardless of the nature of stimulation that it has been exposed to. †

LaTeX : A document preparation system. When writing, the writer uses plain-text as opposed to the formatted text found in WYSIWYG (“what you see is what you get”) word processors like Microsoft Word, LibreOffice Writer, or Apple Pages. The writer uses markup tagging conventions to define the general structure of a document (such as article, book, or letter), to stylize text throughout a document (such as bold and italics), and to add citations and cross-references. A TeX distribution such as TeX Live or MikTeX is used to produce an output file (such as PDF or DVI) suitable for printing or digital distribution. † ℹ︎ latex-project.org

Launch : The (usually public) release of a new software or hardware product.

Law of Conservation of Complexity : → Tesler’s Law

Layout : In web design, a part of graphic design that deals in the arrangement of visual elements on a (web) page. Layout generally involves organizational principles of composition to achieve specific communication objectives. A high-level page layout involves deciding on the overall arrangement of text and images, and possibly on the size or shape of the medium. Layout requires intelligence, sentience, and creativity, and is informed by culture, psychology, and what the document authors and editors wish to communicate and emphasize. † : In web development, the rendering phase during which the position and size of each object is being calculated.

Layout engine : → Browser engine

Layout table : An HTML table used not for intended functional purposes (for tabular data), but for layout. Using tables for layout, often in conjunction with spacer images, is a popular web design method from the 1990s and early 2000s that is largely not in use anymore.

Lazy loading : A design pattern commonly used in computer programming to defer initialization of an object until the point at which it is needed. Lazy loading can contribute to efficiency in the program’s operation if properly and appropriately used. This makes it ideal in use cases where network content is accessed and initialization times are to be kept at a minimum, such as in the case of web pages. The opposite of lazy loading is eager loading. †

LCP : → Largest Contentful Paint

LCU : → Load Balancer Capacity Unit

LCWD : → Last Call Working Draft

LDAP : → Lightweight Directory Access Protocol

Lead time : The latency between the initiation and completion of a process. For example, the lead time between the placement of an order and delivery of a new car by a given manufacturer might be between two weeks and six months, depending on various particularities. Manufacturing lead time, as another example, may be defined as the total time required to manufacture an item, including order preparation time, queue time, setup time, run time, move time, inspection time, and put-away time. †

Leading : The space between adjacent lines of type; the exact definition varies. In hand typesetting, leading is the thin strips of lead that were inserted between lines of type in the composing stick to increase the vertical distance between them. The thickness of the strip is called leading and is equal to the difference between the size of the type and the distance from one baseline to the next. For instance, given a type size of 10 points and a distance between baselines of 12 points, the leading would be 2 points. In CSS, leading refers to the difference between the computed values of font-size and line-height. †

Lean : A business methodology that aims to provide a new way to think about how to organize human activities to deliver more benefits to society and value to individuals while eliminating waste. The term “lean thinking” was coined by James P. Womack and Daniel T. Jones to capture the essence of their in-depth study of Toyota’s fabled Toyota Production System. Lean thinking is a way of thinking about an activity and seeing the waste inadvertently generated by the way the process is organized. It uses the concepts of value, value streams, and flow. †

Left-to-right : A script in which writing starts from the left of a page and continues to the right. †

Legibility : The ease with which a reader can recognize individual characters in text. Aspects of type design that affect legibility include x-height, character shapes, stroke contrast, the size of counters, serifs, or lack thereof, and weight. Not to be confused with readability. †

Less/LESS : A dynamic preprocessor style sheet language that can be compiled into Cascading Style Sheets (CSS) and run on the client or server side. The indented syntax of Less is a nested meta-language, as valid CSS is valid Less code with the same semantics. Less provides variables, nesting, mixins, operators, and functions. The main difference between Less and other CSS precompilers is that Less allows real-time compilation via less.js by the browser. Less was first released in 2009. † ℹ︎ lesscss.org

LeSS : → Large-Scale Scrum

Let’s Encrypt : A non-profit certificate authority run by Internet Security Research Group (ISRG) that provides X.509 certificates for Transport Layer Security (TLS) encryption at no charge. Certificate are valid for 90 days, during which renewal can take place at any time. The offer is accompanied by an automated process designed to overcome manual creation, validation, signing, installation, and renewal of certificates for secure websites. Let’s Encrypt was launched in 2016. † ℹ︎ letsencrypt.org

Letter spacing : An optically consistent degree of increase (or sometimes decrease) of space between letters to affect visual density in a line or block of text. Letter spacing should not be confused with kerning. Letter spacing refers to a uniform adjustment to the spacing of a word or block of text affecting its density and texture. †

Lexical scope : Name resolution depending on the location in the source code and the lexical context (also called static context), which is defined by where the named variable or function is defined. In lexical scope, if a variable name’s scope is a certain function, then its scope is the program text of the function definition; within that text, the variable name exists, and is bound to the variable’s value, but outside that text, the variable name does not exist. †

Library : Typically used in connection with JavaScript, a collection of pre-written scripts which allows for easier development of JavaScript-based applications. †

Library World Wide Web : A modular client-side web API for Unix and Windows. “libwww” is also the name of the reference implementation of the libwww API. It has been used for applications of varying sizes, including web browsers, editors, Internet bots, and batch tools. libwww was first released in 1992. † ℹ︎ w3.org/Library

libwww : → Library World Wide Web

LIFO : → Last In, First Out

Ligature : The joining of two or more graphemes or letters as a single glyph. An example is the character “æ” as used in English, in which the letters “a” and “e” are joined. The common ampersand (“&”) developed from a ligature in which the handwritten Latin letters “e” and “t” (spelling “et,” from the Latin for “and”) were combined. †

Light Mode : A color scheme that uses dark-colored text, icons, and interface elements on a light background. Often a display default.

Lighthouse : An automated tool for measuring the quality of web pages. Lighthouse audits performance, accessibility, development best practices, and search engine optimization, and it includes the ability to test progressive web apps (PWAs) for PWA compliance. Lighthouse is developed by Google. † ℹ︎ is.gd/cMiBtJ

Lightweight Directory Access Protocol : An industry-standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network. Directory services play an important role in developing intranet and Internet applications by allowing the sharing of information about users, systems, networks, services, and applications throughout the network. A common use of LDAP is to provide a central place to store usernames and passwords. This allows many different applications and services to connect to the LDAP server to validate users. †

Lightweight markup language : A markup language with simple, unobtrusive syntax. A lightweight markup language (LML) is designed to be easy to write using any generic text editor and easy to read in its raw form. LMLs are used in applications where it may be necessary to read the raw document as well as the final rendered output. Examples include BBCode, Markdown, and Textile. †

Likert scale : A psychometric scale, typically ranging from “strongly disagree” to “strongly agree,” that is commonly involved in research that employs questionnaires. A Likert scale is the most widely used approach to scaling responses in survey research, such that the term is often used interchangeably with “rating scale.” The Likert scale is named after its inventor, psychologist Rensis Likert. †

Line box : A line (rectangular area) formed by inline boxes.

Line ending : → Newline

Line feed : → Newline

Line spacing : → Leading

Line terminator : → Newline

Linear Responsibility Chart : → Responsibility Assignment Matrix

Lines of Code : A software metric used to measure the size of a computer program by counting the number of lines in the text of the program’s source code. LOC (and SLOC, Source Lines of Code) is typically used to predict the amount of effort that will be required to develop a program, as well as to estimate programming productivity or maintainability once the software is produced. †

Link : A reference from one web resource to another web resource, established through the use of an anchor.

Link equity : The search engine optimization (SEO) concept of links passing authority and value to the respective link target.

Link farm : Any group of websites that hyperlink to other sites in the group for the purpose of increasing SERP rankings. Although some link farms can be created by hand, most are created through automated programs and services. A link farm is a form of spamming the index of a web search engine (sometimes called spamdexing). †

Link juice : → Link equity

Link rot : The phenomenon of hyperlinks tending over time to cease to point to their originally targeted file, web page, or server due to that resource being relocated or becoming permanently unavailable. A link that no longer points to its target, often called a broken or dead link, is a specific form of dangling pointer. The rate of link rot is a subject of study and research due to its significance to the Internet’s ability to preserve information. Estimates of that rate vary dramatically between studies. †

Linked Data : Structured data which is interlinked with other data so it becomes more useful through semantic queries. Linked Data builds upon standard web technologies such as HTTP, RDF, and URIs, but rather than using them to serve web pages only for human readers, it extends them to share information in a way that can be read automatically by computers. Part of the vision of Linked Data is for the Internet to become a global database. †

Linter : A tool that analyzes source code to flag programming errors, bugs, stylistic errors, and suspicious constructs. The term “lint” originates from a Unix utility built in 1978 that examined C language source code. †

Linting : The processing of source code through a linter.

Linux : A family of Unix-like operating systems based on the Linux kernel, an operating system kernel first released in 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution. Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Popular Linux distributions include Debian, Fedora, and Ubuntu. Linux was originally developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system. Linux is the leading operating system on servers and other big iron systems such as mainframe computers, and the only OS used on TOP500 supercomputers. Linux is one of the most prominent examples of free and open source software collaboration. †

Linux Standard Base : A joint project by several Linux distributions under the organizational structure of the Linux Foundation to standardize the software system structure, including the Filesystem Hierarchy Standard used in the Linux kernel. The LSB is based on the POSIX specification, the Single UNIX Specification (SUS), and several other open standards, but extends them in certain areas. †

Linux, Apache, MySQL, PHP/Perl/Python : An archetypal model of web service stacks, named as an acronym (“LAMP”) of the names of its original four open source components: the Linux operating system, the Apache HTTP Server, the MySQL relational database management system (RDBMS), and the PHP programming language. The LAMP components are largely interchangeable and not limited to the original selection. As a solution stack, LAMP is suitable for building dynamic websites and applications. †

Liquid : A web design approach in which page elements have a variable as opposed to a fixed width. Liquid design is a predecessor of responsive design.

LIS : → Location information server

Liskov Substitution Principle : A particular definition of a subtyping relation, called (strong) behavioral subtyping, that was initially introduced in 1987 by Barbara Liskov. The Liskov Substitution Principle is a semantic rather than merely syntactic relation, because it intends to guarantee semantic interoperability of types in a hierarchy, particularly of object types. Liskov’s notion of a behavioral subtype defines a notion of substitutability for objects; that is, if S is a subtype of T, then objects of type T in a program may be replaced with objects of type S without altering any of the desirable properties of that program (e.g., correctness). †

Lisp/LISP : A family of programming languages with a long history and a distinctive, fully parenthesized prefix notation. Originally specified in 1958, Lisp is the second-oldest high-level programming language in widespread use today; only Fortran is older, by one year. The name “LISP” derives from “LISt Processor.” Lisp was originally created as a practical mathematical notation for computer programs. It has changed since its early days, and many dialects have existed over its history. Today, the best-known general-purpose Lisp dialects are Racket, Common Lisp, Scheme, and Clojure. †

Lit : A library for building web components. Lit, or “Lit 2.0,” was released in 2021. ℹ︎ lit.dev

Lite Mode : A data saving mode in the Chrome browser, formerly called “Data Saver.”

LitElement : A JavaScript class for creating web components. Since 2021, LitElement is a part of Lit. ℹ︎ is.gd/3Xte9p

Literal : A notation for representing a fixed value in source code. Almost all programming languages have notations for atomic values such as integers, floating-point numbers, and strings, and usually for Booleans and characters; some also have notations for elements of enumerated types and compound values such as arrays, records, and objects. An anonymous function is a literal for the function type. †

Little’s Law : A theorem by John Little which states that the long-term average number L of customers in a stationary system is equal to the long-term average effective arrival rate λ multiplied by the average time W that a customer spends in the system: L = λ/W. The result applies to any system, and particularly, it applies to systems within systems. †

LML : → Lightweight markup language

Load balancer : → Load balancing

Load Balancer Capacity Unit : A unit used to measure Amazon load balancer processing and billing. LCUs are based on up to four dimensions, depending on the type of load balancer: new connections or flows, active connections or flows, processed bytes, and rule evaluations.

Load balancing : The process of distributing a set of tasks over a set of resources (computing units), with the aim of making their overall processing more efficient. Load balancing can optimize the response time and avoid unevenly overloading compute nodes while other compute nodes are left idle. †

Load time : The time it takes for a page to load, measured from navigation start to the start of the load event. While page load time appears like the perfect web performance metric, it is not. Load times can vary greatly between users depending on device capabilities, network conditions, and, to a lesser extent, distance from the server. The development environment, where page load time is measured, is likely an optimal experience, not reflective of users’ reality. In addition, web performance is not just about when the load event happens; it is also about perceived performance, responsiveness, jank, and jitter. ‡

LOC : → Lines of Code

Local : → Local scope

Local area network : A computer network that interconnects computers within a limited area such as a residence, laboratory, school, university campus, or office building. By contrast, a wide area network (WAN) covers a larger geographic distance. Ethernet and Wi-Fi are the two most common technologies in use for local area networks. †

Local scope : A characteristic of variables that makes them local (i.e., the variable name is only bound to its value within a scope which is not the global scope). ‡

Local storage : Web storage data that is per-origin and available to all scripts loaded from pages from the same origin, and that persists after the browser is closed. †

Local variable : A variable that is given local scope. Local variable references in the function or block in which it is declared override the same variable name in the larger scope. In programming languages with only two levels of visibility, local variables are contrasted with global variables. On the other hand, many ALGOL-derived languages allow any number of nested levels of visibility, with private variables, functions, constants, and types hidden within them, either by nested blocks or nested functions. Local variables are fundamental to procedural programming, and more generally modular programming. Variables of local scope are used to avoid issues with side effects that can occur with global variables. †

Local-part : The first part of an email address. It may use any of the following ASCII characters: uppercase and lowercase Latin letters “A” to “Z” and “a” to “z”; digits “0” to “9”; the printable characters “!”, “#”, “$”, “%”, “&”, “'”, “*”, “+”, “-”, “/”, “=”, “?”, “^”, “_”, “`”, “{”, “|”, “}”, and “~”; and dots (“.”), provided that a dot is not the first or last character unless quoted, and provided also that it does not appear consecutively unless quoted (i.e., [email protected] is not allowed). †

Locale : A set of parameters that defines the user’s language, region, and any special variant preferences that the user wants to see in their user interface. Usually a locale identifier consists of at least a language code and a country or region code. †

Localization : The process of adapting internationalized software for a specific region or language by translating text and adding locale-specific components. Localization (which is potentially performed multiple times, for different locales) uses the infrastructure or flexibility provided by internationalization (which is ideally performed only once before localization, or as an integral part of ongoing development). †

Location information server : A network node originally defined in the U.S. National Emergency Number Association’s i2 network architecture that addresses the intermediate solution for providing e911 emergency service for users of VoIP telephony. The LIS is the node that determines the location of the VoIP terminal. Beyond the NENA architecture and VoIP, the LIS is capable of providing location information to any IP device within its served access network. †

Lock file : → File locking

Log file : A file that records either events that occur in an operating system or other software runs, or messages between different users of a communication software. In the simplest case, messages are written to a single log file. A transaction log is a file (i.e., log) of the communications between a system and the users of that system, or a data collection method that automatically captures the type, content, or time of transactions made by a person from a terminal with that system. Many operating systems, software frameworks and programs include a logging system. A widely used logging standard is syslog. †

Logging : The act of keeping a log file. †

Logical properties : A CSS module introducing properties and values that provide the ability to control layout through logical, rather than physical, direction, and dimension mappings. The module also defines logical properties and values for properties previously defined in CSS 2.1. ‡ ℹ︎ w3.org/TR/css-logical-1

Login : The option, process, or credentials by which an individual gains access to a computer system. The user credentials are typically some form of username and a matching password, and these credentials themselves are sometimes referred to as a “login.” In practice, modern secure systems often require a second factor for extra security, like email or SMS confirmation. †

Logon : → Login

Long task : Any uninterrupted period where the main UI thread is busy for 50 ms or longer. Common examples include long running event handlers, expensive reflows and other re-renders, and work the browser does between different turns of the event loop. ‡ ℹ︎ w3c.github.io/longtasks

Long-Term Support : A product lifecycle management policy in which a stable release of computer software is maintained for a longer period of time than the standard edition. The term is typically reserved for open source software, where it describes a software edition that is supported for months or years longer than the software’s standard edition. †

longdesc : An obsolete HTML attribute that allowed to add a URL to a long description of an image (as defined by the img element). It is instead recommended to use a standard a element to link to the respective description.

Look and feel : A term used with respect to a graphical user interface and comprises aspects of its design, including elements such as colors, shapes, layout, and typefaces (the “look”), as well as the behavior of dynamic elements such as buttons, boxes, and menus (the “feel”). “Look and feel” is used in reference to both software and websites. †

Loop : A sequence of statements which is specified once but which may be carried out several times in succession. The code “inside” the loop (the body of the loop) is obeyed a specified number of times, or once for each of a collection of items, or until some condition is met, or indefinitely. In functional programming languages loops can be expressed by using recursion or fixed point iteration rather than explicit looping constructs. Examples for loops include for loops, while and do while loops, foreach, and infinite loops. †

Lorem ipsum : → Placeholder text

Lossless : A class of data compression algorithms that allows the original data to be perfectly reconstructed from the compressed data. Lossless compression is used in cases where it is important that the original and the decompressed data be identical, or where deviations from the original data would be unfavorable. Typical examples are executable programs, text documents, and source code. Some image file formats, like PNG or GIF, use only lossless compression. †

Lossy : A class of data encoding methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size for storing, handling, and transmitting content. Well-designed lossy compression technology often reduces file sizes significantly before degradation is noticed by the end user. Even when noticeable by the user, further data reduction may be desirable (e.g., for real-time communication, to reduce transmission times, or to reduce storage needs). Lossy compression is most commonly used to compress multimedia data (audio, video, and images), especially in applications such as streaming media and Internet telephony. †

Love-at-first-sight pattern : A pattern of user behavior in which the gaze of a user, as determined by eye tracking, predominantly fixates on one item, like a search engine result.

Low vision : → Visual impairment

LRC : → Linear Responsibility Chart

LSB : → Linux Standard Base

LTR : → Left-to-right

LTS : → Long-Term Support

Lynx : A customizable text-based web browser for use on cursor-addressable character cell terminals. Lynx was released in 1992; as of 2019, it is the oldest web browser still in general use and active development. † ℹ︎ lynx.invisible-island.net

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