*Selenium is an opensource project so many people work together to bring up that project. It can automate a browser, the way we automate is in our hands. *


  For example, for a Facebook application to upload a profile picture everyday whenever we login and share it. This can be achieved by selenium automation, but we cannot use selenium outside the browser everything has to be done on browser itself.


 Before this tool mercury was ruling the industry but now it has become paid source so now everyone started using selenium