PHP stands for  Hypertext Preprocessor,  which is a programming language. Previously it stood for  Personal Home Page. PHP is an open source server side script that can be used on different platforms like Linux, Windows and Unix. The main purpose of PHP is to  generate web pages dynamically and quickly. The scripts are directly placed into  HTML files. PHP is simpler to learn and works smoothly on most servers that are used today, like  Apache  and IIS.

When considering PHP, it first needs to be decided what it is to be used for.  The three main purposes for PHP are server side scripting, desktop applications and command line scripting. For server side scripting, PHP will be required with a web server as well as a web browser. Command line scripting needs only command line executable. Whereas desktop applications will require the PHP-GTK extension which  is not included in the official distribution of PHP.

Before using, examine the security of running PHP on a web server. Although PHP is more secure then Perl or C,  when there is involvement of accessing files, executing commands and open server network connections, it can be insecure. It is necessary to select the correct configuration options.

Some of the features of PHP makes it powerful for writing CGI programs in.  When PHP runs as an Apache module, only then is  HTTP authentication available.  PHP supports cookies which are data stored on remote browsers and sessions preserving some of that over various accesses. In reviewing, there are are a large number of PHP commands though most are organized in these main groups: Database, Arrays, File Handling, Date and Time, Sessions and Cookies, Mathematical, Text and System Commands.

There are many informative online tutorial sources to learn PHP programming as well as numerous books on the subject.