PHP

PHP was previously known as Personal Home Page. It was developed by Rasmus Lerdorf. PHP grew over the years and is now widely known and used as PHP:Hypertext Preprocessor. It is used in today's world to build dynamic data-driven web pages. Users expect exciting and useful web pages to which they will return again and again. Administrators and developers want websites that are easy to maintain and update, but, more importantly, load quickly and do not contain bugs. In programming, a bug is an error or section of code that does not function as required and needs to be fixed. This is where PHP and MySQL come in. Developing exciting, fast, dynamic, data-driven web pages.
PHP is an open source scripting language that is used to develop dynamic web pages that can be embedded into HTML.  Embedding PHP into HTML means PHP scripts can be added to HTML pages, the output of which will be dynamic and functioning HTML pages. The script section is only called once an event is triggered. For example, when a user submits  a form, that specific PHP command will be sent to the PHP parser.
PHP is a server side, cross-platform language. For example, PHP can be built as an Apache component that runs as a Common Getaway Interface(CGI). All PHP events occur on the server side. Cross-platform means that PHP can function on most operating systems. PHP can be used to send HTTP headers, set cookies, manage authentication, and redirect users. PHP is compatible with most databases and can be integrated with a variety of external libraries that allow users to generate PDF documents as well s parse XML files.
The PHP syntax looks familiar to that of C or Perl. There is no need to declare any variable before they are used. PHP consists of object oriented functions that provide organization and encapsulation to any PHP script. The following are the three main uses in which scripts can be used
 Server side scripting - This is the most popular way of using PHP. There are three components needed to work with server side scripting.
. A PHP parser(CGI or server module)
. web browser
. A running web server
Command line scripting - This is used when the PHP script is run without a server or browser. Only the parser is used when using command line scripting.

Writing desktop applications - This method is not used regularly by PHP but it is possible to create desktop applications with a Graphical user interface.