First of all it is open-source project that provide single interface to write scripts in so many programming language like python, java, perl, ruby, C# etc. Second thing, it is open-source so anyone can contribute in it from all over the world. It is used for automation testing for high-end application.

whatnot, many features of selenium are awesome when compared to paid solutions out there, it solves a lot of daily web automation needs in many companies, we are using selenium in multiple projects across the organization and we have created our in-house wrapper framework around it and I can say selenium is reliable in most of the cases. Though it is open source there is a constant updates from the community and lot of new features like auto healing scripts and many more.

easy to use and understand and it's good.