What is Mercurial?
Mercurial is dedicated to speed and efficiency with a sane user interface. It is written in Python. Mercurial's implementation and data structures are designed to be fast. You can generate diffs between revisions, or jump back in time within seconds.
Mercurial is a tool in the Version Control System category of a tech stack.
Why developers like Mercurial
A lot easier to extend than git
Easy-to-grasp system with nice tools
Works on windows natively without cygwin nonsense
Written in python
Better than Git
Better than svn