Selenium consists of

- Selenium Core
- Selenium RC
- Selenium Grid
- Selenium on Rails
- Selenium IDE

Selenium IDE:

Selenium IDE is a complete Integrated Development Environment (IDE) for Selenium tests (previously known as Selenium Recorder). Firefox extension that allows recording and editing of tests. It allows easier development of tests. It can output Ruby for it’s Ruby based (Application Programming Interface) API.

Selenium IDE Features:

- Record and playback
- Intelligent field selection will use IDs, names, or XPath as needed
- Auto complete for all common Selenium commands
- Walk through test cases and test suites.
- Debug and set breakpoints
- Save tests as HTML, Ruby scripts, or other formats
- Support for Selenium user-extensions.js file
- Option to automatically assert the title of every page
- Rollup common commands

Selenium IDE License:

Selenium was developed by a team of programmers and testers at Thought Works. Selenium is open source software, released under the Apache 2.0 license and can be downloaded and used without charge. The Selenium Grid provides a hub allowing the running of multiple Selenium tests concurrently  on any number of local or remote systems, thus minimizing test execution time.