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Introduction
PHP is a server-side programming language used for creating dynamic web sites and
interactive web applications. The acronym PHP originally stood for Personal Home Page,
but as its functionality grew, this was changed to PHP: Hypertext Preprocessor. This
recursive acronym comes from the fact that it takes PHP code as input and produces
HTML as output. This means that users do not need to install any software to view
PHP-generated web pages. All that is required is that the web server has PHP installed to
interpret the script.
In contrast with HTML sites, PHP sites are dynamically generated. Instead of the site
being made up of a large number of static HTML files, a PHP site may consist of only a
handful of template files. The template files describe only the structure of the site using
PHP code, while the web content is pulled from a database and the style formatting
is from Cascading Style Sheets (CSS). This allows for site-wide changes from a single
location, providing a flexible web site that is easy to design, maintain, and update.
When creating web sites with PHP, a content management system (CMS) is generally
used. A CMS provides a fully integrated platform for web site development consisting
of a back end and a front end. The front end is what visitors see when they arrive at the
site, whereas the back end is where the site is configured, updated, and managed by an
administrator. The back end also allows a web developer to change template files and
modify plugins to more extensively customize the functionality and structure of the site.
Examples of free PHP-based CMS solutions include WordPress, Joomla, ModX, and
Drupal, with WordPress being the most popular and accounting for more than half of the
CMS market.
The first version of PHP was created by Rasmus Lerdorf and released in 1995. Since
then, PHP has evolved greatly from a simple scripting language to a fully featured web
programming language. The official implementation is now released by The PHP Group,
with PHP 7 being the most recent version as of this writing. The language may be used
free of charge and is open source, allowing developers to extend it for their own use or to
contribute to its development.
PHP is by far the most popular server-side programming language in use today.
It holds a growing 80% market share when compared with other server-side technologies,
such as ASP.NET, Java, Ruby, and Perl. One of the reasons for the widespread adoption
of PHP is its platform independence. It can be installed on all major web servers and
operating systems, and used with any major database system. Another strong feature
of PHP is its simple-to-use syntax based on C and Perl, which is easy for a newcomer to
learn; however, PHP also offers many advanced features for the professional programmer.
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