Firefox, Chrome, Internet Explorer, Safari
Selenium is a free to use tool.
Support for a large number of programming languages
Java, C #, Ruby, Python, Pearl
Compatible with all major platforms
Windows, Mac OS, Linux
Massive public support
A huge number of users and, accordingly, massive public support.
Selenium WebDriver is a browser driver, that is, a program library that does not have a user interface, which allows various other programs to interact with the browser, control its behavior, receive some data from the browser and force the browser to execute some kind of command.