Selenium IDE (Integrated Development Environment) works similar to commercial tools like QTP, Silk Test and Test Partner etc.
 The below mentioned points describes well about Selenium IDE.
1. Selenium IDE is a Firefox add-on.
2. Selenium IDE can support recording the clicks, typing, and other actions to make a test cases.
3. Using Selenium IDE A Tester can play back the test cases in the Firefox browser
4. Selenium IDE supports exporting the test cases and suites to Selenium RC.
5. Debugging of the test cases with step-by-step can be done
6. breakpoint insertion is possible
7. Page abstraction functionality is supported by Selenium IDE
8. Selenium IDE can supports an extensibility capability allowing the use of add-ons or user extensions that expand the functionality of Selenium IDE.