.PHP File Extension
What is a PHP file?
A PHP file is a webpage that contains PHP (Hypertext Preprocessor) code. It may include PHP functions that can process online forms, get the date and time, or access information from a database, such as a MySQL database.
PHP files are typically only used by web developers who are creating or modifying PHP files when developing webpages with extended functionality. However, average users may download PHP files from a webpage using a web browser, such as Google Chrome or Mozilla Firefox.
The PHP code within the webpage is processed (parsed) by a PHP engine on the web server, which dynamically generates HTML. The HTML, which contains the webpage content, is then sent to the user's web browser. Therefore, the user never sees the actual PHP code contained in the webpage, even when viewing the page source.
Common PHP Filenames
index.php - Often the default file to be loaded when a client Web browser requests a directory from a PHP-enabled Web server. For example, if http://sampledomain.com/ is requested, http://sampledomain.com/index.php is loaded.
How to open a PHP file
You can open and edit PHP files with various source code editors and PHP-dedicated applications with IDEs. Examples of these programs include Eclipse PHP Development Tools (Windows and macOS), MPSoftware phpDesigner (Windows), Adobe Dreamweaver (Windows and macOS), Zend Studio (multiplatform), and Microsoft Visual Studio Code (multiplatform).
Since PHP files are saved in plain text, you can also open them with text editors, including Microsoft Notepad (bundled with Windows) and Apple TextEdit (bundled with macOS).