Joel Spolsky, one of our co-founders, wrote a great introduction to DVCS and Mercurial.

There is also a solid “Mercurial for Beginners” guide on StackOverflow that contains answers to most basic questions: http://stackoverflow.com/questions/1170338/mercurial-for-beginners-the-definitive-practical-guide. If you have helpful information to add, please do so there!

The book Mercurial: The Definitive Guide is quite good for getting your hands dirty with Mercurial and DVCS. Luckily, it’s also available online for you to read, free of charge.

Of course, the Wikipedia article on DVCS may also be of use if you’re used to using (or have never used) a traditional version control system.