CVS (the Concurrent Version System) is the tool we use for keeping our sources under control. Every change (with accompanying log message explaining its purpose) from FreeBSD 2.0 to the present is stored here. It can be easily viewed from the web interface mentioned below. To obtain a complete copy of the FreeBSD CVS repository or any of the development branches inside it, you may choose any one of following options:

• CVSup if you are looking for on-demand, low overhead access using a custom utility (written in Modula-3 no less).
• anoncvs if you are looking for on-demand access that has higher overhead than cvsup (in terms of wall time and bytes transferred) but is easier to use for checking out small pieces of the tree and requires nothing more than the cvs tools already bundled with FreeBSD.
• CTM if you are looking for very low overhead, batch-mode access (basically, patches through email).
• The web interface if you are looking to simply browse the repository in search of a specific change or file revision.

Mirrors of the CVS web interface are available in Czech republic, Denmark, Japan, USA/California and Ukraine.