Although labeled as an automation testing tool, Selenium isn’t a standalone tool. Instead, it is a package of several tools, and thus a testing suite. The Selenium suite has the following components:
Selenium IDE – Distributed as a Firefox plugin, Selenium IDE serves as a record and playback tool.
Selenium Grid – Allows distributing test execution across multiple platforms and environments concurrently.
Selenium RC – A server that allows users to create test scripts in a desirable programming language. Selenium RC also permits executing test scripts across a diverse range of web browsers.
Selenium WebDriver – Communicated directly with the web browser in addition to using its native compatibility to automate.