While there were several DVCSs that we could support, our decision to support Mercurial was based on two key reasons. The primary reason was to support our large base of existing Subversion users that want to use a distributed version control system. For these users we felt that Mercurial had the lowest barrier to adoption because of its similar command set, great documentation (including a great online book), and excellent tools such as Tortoise Hg. Second, given that Google Code's infrastructure is built for HTTP-based services, we found that Mercurial had the best protocol and performance characteristics for HTTP support. For more information, see our analysis.