Hypertext Processor (or PHP) is a general purpose scripting language that was designed to produce dynamic web pages. It has the capability to be embedded in HTML pages and usually runs on a web server. It also has the capability to deploy on most web servers on almost every operating system and platform –which is free of charge for every user.
PHP was designed specifically for web development. Any PHP code is executed through the PHP runtime and generally used to create dynamic web page content. It also can function as command-line scripting and client-side GUI applications. The language acts as a filter to take input from a file or stream that contains text and/or PHP instructions and outputs a different stream of data (most commonly of the HTML format). However, there have been substantial levels of vulnerabilities in the PHP security (last charted at 35% in 2008). Such vulnerabilities can be remotely exploited, allowing hackers to steal and/or destroy data from data sources linked to the web server.
1. AJAX is a group of technologies that allows web applications to retrieve data from the server asynchronously; PHP is a scripting language designed to produce dynamic web pages.