Selenium 2 is the second major release of Selenium, an open source framework for testing web applications. A major difference between Selenium 1 and Selenium 2 is the latter's use of WebDriver.
Selenium is a portable software testing framework for web applications. Selenium provides a record/playback tool for authoring tests without learning a test scripting language. Selenium provides a test domain specific language (DSL) to write tests in a number of popular programming languages, including Java, C#, Ruby, Groovy, Python, PHP, and Perl. Test playback is possible in most modern web browsers. Selenium deploys on Windows, Linux, and Macintosh platforms.
Selenium was originally developed by Jason Huggins, who was later joined by other programmers and testers at ThoughtWorks. It is open source software, released under the Apache 2.0 license and can be downloaded and used without charge.
Selenium IDE is a complete integrated development environment (IDE) for Selenium tests. It is implemented as a firefox extension, and allows recording, editing, and debugging tests. It was previously known as Selenium Recorder. Selenium-IDE was originally created by Shinya Kasatani and donated to the Selenium project in 2006.