FreeBSD Source:

This is the top level of the FreeBSD source directory. This file
was last revised on:
FreeBSD

For copyright information, please see the file COPYRIGHT in this
directory (additional copyright information also exists for some
sources in this tree - please see the specific source directories for
more information).

The Makefile in this directory supports a number of targets for
building components (or all) of the FreeBSD source tree. See build(7)
and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html
for more information, including setting make(1) variables.

The buildkernel and installkernel targets build and install
the kernel and the modules (see below). Please see the top of
the Makefile in this directory for more information on the
standard build targets and compile-time flags.

Building a kernel is a somewhat more involved process. See build(7), config(8),
and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html
for more information.

Note: If you want to build and install the kernel with the
buildkernel and installkernel targets, you might need to build
world before. More information is available in the handbook.

The kernel configuration files reside in the sys/<arch>/conf
sub-directory. GENERIC is the default configuration used in release builds.
NOTES contains entries and documentation for all possible
devices, not just those commonly used.

Source Roadmap:

bin				System/user commands.

cddl			Various commands and libraries under the Common Development  
				and Distribution License.

contrib			Packages contributed by 3rd parties.

crypto			Cryptography stuff (see crypto/README).

etc				Template files for /etc.

gnu				Various commands and libraries under the GNU Public License.  
				Please see gnu/COPYING* for more information.

include			System include files.

kerberos5		Kerberos5 (Heimdal) package.

lib				System libraries.

libexec			System daemons.

release			Release building Makefile & associated tools.

rescue			Build system for statically linked /rescue utilities.

sbin			System commands.

secure			Cryptographic libraries and commands.

share			Shared resources.

sys				Kernel sources.

tests			Regression tests which can be run by Kyua.  See tests/README
				for additional information.

tools			Utilities for regression testing and miscellaneous tasks.

usr.bin			User commands.

usr.sbin		System administration commands.

For information on synchronizing your source tree with one or more of
the FreeBSD Project's development branches, please see:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html