Difference between Selenium IDE, Selenium RC, Selenium Webdriver

Selenium IDE	Selenium RC	Selenium Web-driver
Only works on Mozilla Firefox	Works on almost all browsers.Does not work on latest version of Firefox/IE	Works on latest versions of almost all browsers - Firefox, IE(6,7,8), Opera, Chrome
Record and play/run tool	No Record and run	No Record and run
No server required to start	Server is required to start	No server required to start
Core engine is JavaScript based	Core engine is JavaScript based	Interacts natively with browser application
Very simple to use. If using User extensions, you require knowledge on java script which makes the work a little bit tough.	Its a simple and small API	Complex and a bit large API as compared to RC
Not at all object oriented	Less Object oriented API	Purely Object oriented API
Cannot move mouse with it	Cannot move mouse with it	Can move mouse cursor
Full xpaths have to be appended with 'xapth=\\' syntax	Full xpaths have to be appended with 'xapth=\\' syntax	No need to append 'xpath=\\'
No Listeners	No Listeners	Implementation of Listeners is provided
Cannot test iPhone/Android applications	Cannot test iPhone/Android applications	Can test iPhone/Android applications
Cannot test iPhone/Android applications	Cannot test iPhone/Android applications	Can test iPhone/Android applications

About Selenium

What is Selenium?

Selenium automates browsers. That's it. What you do with that power is entirely up to you. Primarily it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) also be automated as well.

Selenium has the support of some of the largest browser vendors who have taken (or are taking) steps to make Selenium a native part of their browser. It is also the core technology in countless other browser automation tools, APIs and frameworks.