File Extension PHP
File extension PHP is most commonly associated with a Hypertext Preprocessor file. PHP files contain server-side scripts written in the PHP language with embedded Hypertext Markup Language (HTML), and are widely used by web developers to build dynamic websites. Though now uncommon, the PHP file extension may also be used to denote a Picture It! project file or a PhotoParade Slideshow, though the default extension of the latter was changed as of version 4 to avoid confusion with PHP scripts.
The majority of PHP files refer to web pages written using the PHP scripting language. PHP is a freely available, general purpose scripting language developed primarily for web-based applications. Its simplicity and cross-platform compatibility has made it a popular language, and is widely used to develop dynamic websites. PHP is a server-side language, and is often used to generate web pages dynamically based on user input, such as from File extension HTML forms, or using back-end databases. Other, similar server-side scripting languages include Microsoft's File extension ASP.NET and Sun Microsystems' JavaServer Pages (File extension JSP).
PHP files are stored in plaintext, and usually contain a mixture of PHP scripts and HTML. These are then parsed and compiled at runtime by a PHP engine which runs on a web server and the output, usually in the form of pure HTML, is sent to the user's web browser. As all script execution takes place server-side, no actual PHP code is sent to the client browser despite the file having the PHP extension.
PHP script files are stored in plaintext, so can be edited using any text editor or website development software such as Adobe Dreamweaver which may offer additional functionality such as syntax highlighting. In order to run a PHP file, it must be executed on a web server with PHP support such as Apache or Microsoft's IIS. The output can be viewed via a standard web browser by navigating to the PHP file on the web server.