Selenium is a product suite consisting of following components :
Selenium IDE – IDE stands for Integrated Development Environment which is a plug-in of web browser Firefox. This is the simplest framework and hence requires the developers to switch to Selenium RC for advanced test cases.
Selenium RC – RC stands for Remote Control which allows the developers to code in the language of their preference. Selenium RC supports multiple programming languages such as Java, C#, Python, etc.
Selenium Grid – Selenium Grid is used to execute parallel tests along with Selenium RC across multiple browsers.