This section is from the "Version Control with Subversion" book, by Ben Collins-Sussman, Brian W. Fitzpatrick and C. Michael Pilato. Also available from Amazon: Version Control with Subversion.
While Subversion's flexibility allows you to layout your
repository in any way that you choose, we recommend that you
create a trunk
directory to hold the
“main line” of development, a
branches
directory to contain branch
copies, and a tags
directory to contain tag
copies, for example:
$ svn list file:///var/svn/repos /trunk /branches /tags
You'll learn more about tags and branches in Chapter 4, Branching and Merging. For details and how to set up multiple projects, see the section called “Repository Layout” and the section called “Planning Your Repository Organization” to read more about “project roots”.