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

WooCommerce is an open source e-commerce plugin for WordPress that was launched on September 27, 2011. 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

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

The eBay API is the heart of the an Application programming interface for interacting directly with the eBay database. The communication occurs over the Internet in the XML format. wikipedia.org

OAuth (Open Authorization) is an open standard for authorization. It allows users to share their private resources (e.g., photos, videos, contact lists) stored on one site with another site without having to hand out their credentials, typically username and password.

An application programming interface (API) is a source code based specification intended to be used as an interface by software components to communicate with each other. An API may include specifications for routines, data structures, object classes, and variables. wikipedia.org

JSON or JavaScript Object Notation, is an open standard format that uses human-readable text to transmit data objects consisting of attribute–value pairs wikipedia.org