XHTML

XHTML is a family of current and future document types and modules that reproduce, subset, and extend HTML 4. XHTML family document types are XML based, and ultimately are designed to work in conjunction with XML-based user agents.

XHTML 1.0 is the first document type in the XHTML family. It is a reformulation of the three HTML 4 document types as applications of XML 1.0. It is intended to be used as a language for content that is both XML-conforming and, if some simple guidelines are followed, operates in HTML 4 conforming user agents. Developers who migrate their content to XHTML 1.0 will realize the following benefits:

• XHTML documents are XML conforming. As such, they are readily viewed, edited, and validated with standard XML tools.
• XHTML documents can be written to operate as well or better than they did before in existing HTML 4-conforming user agents as well as in new, XHTML 1.0 conforming user agents.
• XHTML documents can utilize applications (e.g. scripts and applets) that rely upon either the HTML Document Object Model or the XML Document Object Model.
• As the XHTML family evolves, documents conforming to XHTML 1.0 will be more likely to interoperate within and among various XHTML environments.

The XHTML family is the next step in the evolution of the Internet. By migrating to XHTML, content developers can enter the XML world with all of its attendant benefits, while still remaining confident in their content's backward and future compatibility.

XML

Extensible Markup Language, abbreviated XML, describes a class of data objects called XML documents and partially describes the behavior of computer programs which process them. XML is an application profile or restricted form of SGML, the Standard Generalized Markup Language. By construction, XML documents are conforming SGML documents.

XML documents are made up of storage units called entities, which contain either parsed or unparsed data. Parsed data is made up of characters, some of which form character data, and some of which form markup. Markup encodes a description of the document's storage layout and logical structure. XML provides a mechanism to impose constraints on the storage layout and logical structure.

CSS

Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can be applied to any kind of XML document, including SVG and XUL.

CSS can be used locally by the readers of web pages to define colors, fonts, layout, and other aspects of document presentation. It is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation (written in CSS). This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, and reduce complexity and repetition in the structural content (such as by allowing for tableless web design). CSS can also allow the same markup page to be presented in different styles for different rendering methods, such as on-screen, in print, by voice (when read out by a speech-based browser or screen reader) and on Braille-based, tactile devices. CSS specifies a priority scheme to determine which style rules apply if more than one rule matches against a particular element. In this so-called cascade, priorities or weights are calculated and assigned to rules, so that the results are predictable.

JavaScript

JavaScript is a scripting language widely used for client-side web development. It is a dynamic, weakly typed, prototype-based language with first-class functions. JavaScript was influenced by many languages and was designed to look like Java, but be easier for non-programmers to work with.

Although best known for its use in websites (as client-side JavaScript), JavaScript is also used to enable scripting access to objects embedded in other applications.

JavaScript, despite the name, is essentially unrelated to the Java programming language, although both have the common C syntax, and JavaScript copies many Java names and naming conventions. The language's name is the result of a co-marketing deal between Netscape and Sun.

AJAX

Ajax, or AJAX (Asynchronous JavaScript and XML), is a group of interrelated web development techniques used to create interactive web applications or rich Internet applications. With Ajax, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page. The use of Ajax has led to an increase in interactive animation on web pages. Data is retrieved using the XMLHttpRequest object or through the use of Remote Scripting in browsers that do not support it. Despite the name, the use of JavaScript and XML is not actually required, nor do the requests need to be asynchronous. The acronym AJAX has thus changed to the term Ajax, which does not represent these specific technologies.

PHP

PHP is a scripting language originally designed for producing dynamic web pages. It has evolved to include a command line interface capability and can be used in standalone graphical applications.

While PHP was originally created by Rasmus Lerdorf in 1995, the main implementation of PHP is now produced by The PHP Group and serves as the de facto standard for PHP as there is no formal specification. PHP is free software released under the PHP License, however it is incompatible with the GNU General Public License (GPL), due to restrictions on the usage of the term PHP.

PHP is a widely-used general-purpose scripting language that is especially suited for web development and can be embedded into HTML. It generally runs on a web server, taking PHP code as its input and creating web pages as output. It can be deployed on most web servers and on almost every operating system and platform free of charge. PHP is installed on more than 20 million websites and 1 million web servers.

SQL

SQL (Structured Query Language) is a database computer language designed for the retrieval and management of data in relational database management systems (RDBMS), database schema creation and modification, and database object access control management.

SQL is a programming language for querying and modifying data and managing databases. SQL was standardized first by the ANSI and later by the ISO. Most database management systems implement a majority of one of these standards and add their proprietary extensions. SQL allows the retrieval, insertion, updating, and deletion of data. A database management system also includes management and administrative functions. Most – if not all – implementations also include a command-line interface (SQL/CLI) that allows for the entry and execution of the language commands, as opposed to only providing an application programming interface (API) intended for access from a graphical user interface (GUI).

The first version of SQL was developed at IBM by Donald D. Chamberlin and Raymond F. Boyce in the early 1970s. This version, initially called SEQUEL, was designed to manipulate and retrieve data stored in IBM's original relational database product, System R. IBM patented their version of SQL in 1985, while the SQL language was not formally standardized until 1986 by the American National Standards Institute (ANSI) as SQL-86. Subsequent versions of the SQL standard have been released by ANSI and as International Organization for Standardization (ISO) standards.

Originally designed as a declarative query and data manipulation language, variations of SQL have been created by SQL database management system (DBMS) vendors that add procedural constructs, flow-of-control statements, user-defined data types, and various other language extensions. With the release of the SQL:1999 standard, many such extensions were formally adopted as part of the SQL language via the SQL Persistent Stored Modules (SQL/PSM) portion of the standard.

Common criticisms of SQL include a perceived lack of cross-platform portability between vendors, inappropriate handling of missing data, and unnecessarily complex and occasionally ambiguous language grammar and semantics.

RSS

RSS is a family of Web feed formats used to publish frequently updated works - such as blog entries, news headlines, audio, and video - in a standardized format. An RSS document (which is called a "feed", "web feed" or "channel") includes full or summarized text, plus metadata such as publishing dates and authorship. Web feeds benefit publishers by letting them syndicate content automatically. They benefit readers who want to subscribe to timely updates from favored websites or to aggregate feeds from many sites into one place. RSS feeds can be read using software called an "RSS reader", "feed reader" or "aggregator", which can be web-based, desktop-based, mobile device or any computerized Internet-connected device. A standardized XML file format allows the information to be published once and viewed by many different programs. The user subscribes to a feed by entering the feed's URI (often referred to informally as a "URL", although technically, those two terms are not exactly synonymous) into the reader or by clicking an RSS icon in a browser that initiates the subscription process. The RSS reader checks the user's subscribed feeds regularly for new work, downloads any updates that it finds, and provides a user interface to monitor and read the feeds.

RSS formats are specified using XML, a generic specification for the creation of data formats. Although RSS formats have evolved since March 1999, the RSS icon first gained widespread use between 2005 and 2006.

WEB 2.0

The term "Web 2.0" describes the changing trends in the use of World Wide Web technology and web design that aim to enhance creativity, communications, secure information sharing, collaboration and functionality of the web. Web 2.0 concepts have led to the development and evolution of web-culture communities and hosted services, such as social-networking sites, video sharing sites, wikis, blogs, and folksonomies. The term first became notable after the O'Reilly Media Web 2.0 conference in 2004. Although the term suggests a new version of the World Wide Web, it does not refer to an update to any technical specifications, but rather to changes in the ways software developers and end-users utilize the Web. According to Tim O'Reilly: "Web 2.0 is the business revolution in the computer industry caused by the move to the Internet as a platform, and an attempt to understand the rules for success on that new platform."

O'Reilly has said that the "2.0" refers to the historical context of web businesses "coming back" after the 2001 collapse of the dot-com bubble, in addition to the distinguishing characteristics of the projects that survived the bust or thrived thereafter.

Tim Berners-Lee, inventor of the World Wide Web, has questioned whether one can use the term in any meaningful way, since many of the technological components of Web 2.0 have existed since the early days of the Web.

DOM

The World Wide Web Consortium (W3C), founded in 1994 to promote open standards for the World Wide Web, brought Netscape Communications and Microsoft together with other companies to develop a standard for browser scripting languages, called "ECMAScript". The first version of the standard was published in 1997. Subsequent releases of JavaScript and JScript would implement the ECMAScript standard for greater cross-browser compatibility.

After the release of ECMAScript, W3C began work on a standardized DOM. The initial DOM standard, known as "DOM Level 1," was recommended by W3C in late 1998. About the same time, Internet Explorer 5.0 shipped with limited support for DOM Level 1. DOM Level 1 provided a complete model for an entire HTML or XML document, including means to change any portion of the document. Non-conformant browsers such as Internet Explorer 4.x and Netscape 4.x were still widely used as late as 2000.

DOM Level 2 was published in late 2000. It introduced the "getElementById" function as well as an event model and support for XML namespaces and CSS. DOM Level 3, the current release of the DOM specification, published in April 2004, added support for XPath and keyboard event handling, as well as an interface for serializing documents as XML.

By 2005, large parts of W3C DOM were well-supported by common ECMAScript-enabled browsers, including Microsoft Internet Explorer version 6 (2001), Gecko-based browsers (like Mozilla, Firefox and Camino), Konqueror, Opera, and Safari.