Chapter 4: Repositories
Chapter 4: Repositories: "A repository is the official place where you store all your source code. It keeps track of all your files, as well as the layout of the directories in which they are stored. It resides on a server where it can be shared by all the members of your team.
But there has to be more. If the definition in the previous paragraph were the whole story, then an SCM repository would be no more than a network file system. A repository is much more than that. A repository contains history.
A file system is two-dimensional: its space is defined by directories and files. In contrast, a repository is three-dimensional: it exists in a continuum defined by directories, files and time. An SCM repository contains every version of your source code that has every existed. The additional dimension creates some rather interesting challenges in the architecture of a repository and the decisions about how it manages data."