PHP
PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language. As of January 2013, PHP was installed on more than 240 million websites (39% of those sampled) and 2.1 million web servers.Originally created by Rasmus Lerdorf in 1994,the reference implementation of PHP (powered by the Zend Engine) is now produced by The PHP Group.While PHP originally stood for Personal Home Page,it now stands for PHP: Hypertext Preprocessor, which is a recursive backronym.
PHP code can be simply mixed with HTML code, or it can be used in combination with various templating engines and web frameworks. PHP code is usually processed by a PHP interpreter, which is usually implemented as a web server's native module or a Common Gateway Interface (CGI) executable. After the PHP code is interpreted and executed, the web server sends resulting output to its client, usually in form of a part of the generated web page; for example, PHP code can generate a web page's HTML code, an image, or some other data. PHP has also evolved to include a command-line interface (CLI) capability and can be used in standalone graphical applications.
The canonical PHP interpreter, powered by the Zend Engine, is free software released under the PHP License. PHP has been widely ported and can be deployed on most web servers on almost every operating system and platform, free of charge.
Despite its popularity, no written specification or standard existed for the PHP language until 2014, leaving the canonical PHP interpreter as a de facto standard. Since 2014, there is ongoing work on creating a formal PHP specification.
JavaScript
JavaScript, also known as ECMAScript (the untrademarked name used for the standard), is a dynamic programming language.It is most commonly used as part of web browsers, whose implementations allow client-side scripts to interact with the user, control the browser, communicate asynchronously, and alter the document content that is displayed. It is also used in server-side network programming with runtime environments such as Node.js, game development and the creation of desktop and mobile applications. With the rise of the single-page web app and JavaScript-heavy sites, it is increasingly being used as a compile target for source-to-source compilers from both dynamic languages and static languages. In particular, Emscripten and highly optimised JIT compilers, in tandem with asm.js that is friendly to AOT compilers like OdinMonkey, have enabled C and C++ programs to be compiled into JavaScript and execute at near-native speeds, causing JavaScript to be considered the "assembly language of the web",according to its creator and others.
JavaScript is classified as a prototype-based scripting language with dynamic typing and first-class functions. This mix of features makes it a multi-paradigm language, supporting object-oriented,imperative, and functional programming styles.
Despite some naming, syntactic, and standard library similarities, JavaScript and Java are otherwise unrelated and have very different semantics. The syntax of JavaScript is actually derived from C, while the semantics and design are influenced by the Self and Scheme programming languages.
JavaScript is also used in environments that aren't web-based, such as PDF documents, site-specific browsers, and desktop widgets. Newer and faster JavaScript virtual machines (VMs) and platforms built upon them have also increased the popularity of JavaScript for server-side web applications. On the client side, JavaScript has been traditionally implemented as an interpreted language, but more recent browsers perform just-in-time compilation.
JavaScript has been standardized in the ECMAScript language specification.
Cascading Style Sheets
Cascading Style Sheets, or CSS, are a way to change the look of HTML and XHTML web pages. CSS was designed by the W3C, and is supported well by most modern web browsers. The current version of CSS is CSS 2. CSS version 3 is currently being worked on. It will introduce new properties like border-radius.
One advantage to using CSS is a web page can still be displayed and understood, even if the CSS is not working or removed.
CSS code is saved in files with the .css file extension.