The version control system Subversion is used by all ASF projects to manage their source code and other resources.
The Forrest "trunk" is where the main development happens. From time-to-time "branches" are used for specific short-term development tasks and later merged to trunk.
For every change, a notification email is automatically sent to the svn@ mailing list. Subscribe to that list or search the archives to keep up-to-date with changes.
Developers can work with the most recent sources rather than a released version, follow the instructions to checkout your working copy.
See other best practice notes.