Defining a Working Copy
An Apache Subversion™ working copy is an ordinary directory tree on your local system, containing a collection of files. You can edit these files however you want, your working copy being your private work area. To make your own changes available to others or incorporate changes made by others, you must explicitly tell Subversion to do so. You can even have multiple working copies of the same project.
A Subversion working copy also contains some extra files, created and maintained by Subversion, to help it keep track of your files. In particular, each directory in your working copy contains a subdirectory named .svn, also known as the working copy administrative directory. This administrative directory contains an unaltered copy of the last updated files from the repository. This copy is usually referred to as the pristine copy or the BASE revision of the working copy. These files help Subversion recognize which files contain unpublished changes, and which files are out-of-date with respect to others' work.
A typical Subversion repository often holds the files (or source code) for several projects. Usually each project is a subdirectory in the repository's file system tree. In this arrangement, a user's working copy usually corresponds to a particular sub-tree of the repository.