PHP is also many web servers like APACHE and many others like WAMP. People works as either module or CGI processor.
Above paragraph told me that using PHP, I have the freedom of selecting operating system and a web server. I have also the choice of using programming method. I can use procedural programming, Object oriented programming or mixture of both.
With PHP you are not limited to output. HTML, you can output images, pdf files and even flash movies. You can also output any text such as XHTML or XML. PHP auto-generates these outputs and you can save them on your file system instead of publishing out.
One of the strongest features is to support for wide range of databases. Writing a database enabled web pages simply by using one of the specific extensions (.sql).
PHP also has support for talking other protocols like LDAP, HTTP and many others. You can also use open row network sockets and internet using any other protocol.
PHP has text processing features, which includes the Perl compatible regular operations and many other tools to parse and access XML documents.