PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. wikipedia.org

MySQL is a relational database management system (RDBMS) that runs as a server providing multi-user access to a number of databases. wikipedia.org

CodeIgniter is an open source web application framework for use in building dynamic web sites with PHP. wikipedia.org

"Model–view–controller (MVC) is a software architectural pattern for implementing user interfaces. It divides a given software application into three interconnected parts, so as to separate internal representations of information from the ways that information is presented to or accepted from the user." wikipedia.org

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. wikipedia.org

Ajax is a group of interrelated web development methods used on the client-side to create asynchronous web applications. wikipedia.org

Authorize.Net is a payment gateway service provider allowing merchants to accept credit card and electronic checks payments through their Web site and over an IP (Internet Protocol) connection. wikipedia.org

jQuery is a cross-browser JavaScript library designed to simplify the client-side scripting of HTML. Its syntax is designed to make it easier to navigate a document, select DOM elements, create animations, handle events, and develop Ajax applications. wikipedia.org

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles. wikipedia.org

Cascading Style Sheets (CSS) is a style sheet language used to describe the presentation (that is, the look and formatting) of a document written in a markup language. wikipedia.org