Celtralized version control systems (cvcss, included cvs, subversion, perforce (?)) have single server that contains all the versioned files.
Distributed version control systems (dvcss: git, mercurial, bazaar, darcs) fully mirror the repository, Every checkout is really a full backup of all the data.
Git - History
Git was initially designed and developed by
Linus Torvalds
for
Linux kernel
development in 2005
Many developers of the
Linux kernel chose to give up access to BitKeeper
The copyright holder of BitKeeper, Larry McVoy, had
withdrawn free use of the product
Torvalds wanted a distributed system
that he could use
like BitKeeper
Git - The Goals
Speed
Simple design
Strong support for non-linear development (thousands of parallel branches)
Fully distributed
Able to handle large projects like the Linux kernel effeciently (speed and data size)