Created by Tom Wilson / @twilson63
Git thinks of its data more like a set of snapshots of a mini filesystem
The mechanism that Git uses for this checksumming is called a SHA-1 hash. This is a 40-character string composed of hexadecimal characters (0–9 and a–f) and calculated based on the contents of a file or directory structure in Git. A SHA-1 hash looks something like this:
24b9da6552252987aa493b52f8696cd6d3b00373
You may have heard that GitHub is a code sharing and publishing service, or that it’s a social networking site for programmers. Both statements are true, but neither explain exactly why GitHub is special.
TechCrunch
http://techcrunch.com/2012/07/14/what-exactly-is-github-anyway/
git + social = github
or
git + collaboration = github