What’s darcs?
Darcs is a version control system, broadly similar to Git, Mercurial and others, but with a simpler conceptual model that many people find less costly to learn and use. If you don’t have a lot of time to spend learning your version control tool, darcs (and darcs hub) may be a good choice.

What’s darcs hub?
Darcs hub is the free darcs repository hosting site. It aims to:
  1.   provide a reliable, usable and evolving hosting and collaboration hub for darcs users
  2.   accelerate the development of darcs and its ecosystem, eg through an easier contribution process and increased visibility and dogfooding.