It is the most widely used server-side language, followed by ASP (see related links). It is particularly common for websites/webapplications that do not require the programming-in-the-large features of JSP or .NET. It is simple and easy to learn, but also powerful. In particular, the development of some Ruby-like frameworks has given more power to PHP developers.
Now a days ,PHP is the most widely-used open-source and general-purpose scripting language.Mainly , PHP was designed to create dynamic and more interactive web pages. It is a server-side scripting language embed with HTML. PHP code in a script can interect with databases, create images, read and write files and talk to remote servers. So the output from PHP code is combined with HTML in script and the result is sent to the user as a
web page.