What is PHP?
PHP is a popular general-purpose open source scripting language that is ideal for web development and can be integrated into HTML. PHP pages contain HTML with embedded code that does "something," as opposed to HTML being output by a large number of commands (as seen in C or Perl).
PHP differs from client-side scripting languages like JavaScript in that its code is run on a server before being converted into HTML and provided to the client. Although the client wouldn't be aware of the underlying code, they would obtain the results of running that script. There is really no way for consumers to guess what you have up your sleeve if you configure your web server to process all of your HTML files with PHP.
What can PHP do?
The short answer is a lot of things. Since PHP is primarily used for server-side scripting, it can do all CGI (Common Gateway Interface) functions, including collecting form data, creating dynamic page content, and sending and receiving cookies. But PHP is considerably more versatile.
There are three main areas where PHP scripts are used:
Server Side Scripting - This is PHP's most established and primary application area. The PHP parser (CGI or server module), a web server, and a web browser are required for this to function. Running the web server and connecting the PHP installation are both required. By accessing the PHP page via the server, you can access the output of the PHP programme using a web browser.
Command line scripting - PHP script can be created to run it independently of a server or browser. To utilise it in this manner, you only need the PHP parser. This method of use is appropriate for scripts that are regularly run by Task Scheduler or cron (on *nix or Linux) (on Windows). Simple text processing tasks can also be accomplished with these programmes.
Writing desktop applications - To construct desktop-based applications, you can employ sophisticated PHP features in your client-side applications. In order to accomplish this, PHP-GTK is used. In this way, you can also create cross-platform applications.