"Linus Torvalds began working on an interim solution called
'git' in the absence of BitKeeper. A README included with the
source describes it as, 'a stupid (but extremely fast) directory
content manager. It doesn't do a whole lot, but what it _does_ do
is track directory contents efficiently.; The documentation goes on
to describe two abstractions used by the tool, an 'object
database,' and a 'current directory cache.' Objects in the object
database are referred to by the SHA1 hash of their zlib compressed
contents. The various supported object types include, 'blobs' which
are simply binary blobs of data with no added verification, 'trees'
which are lists of objects sorted by name, and 'changesets' which
provide a historical view of an object describing 'how we got
there, and why.' The current directory cache is a binary file
'which contains an efficient representation of a virtual directory
content at some random time...'"