Gentoo Linux is a Linux source distribution. This means unlike other distros, software doesn’t come as compiled binaries but as ebuilds, recipes describing how the software can be compiled and linked. Installing software therefore takes longer but is optimized for the underlying hardware.
The real power of Gentoo, however, lies with it’s package manager Portage. It traces dependencies by far more reliably than other package managers and features per ebuild customization through USE flags.
Gentoo comes in a few flavours, most notably Gentoo Linux as the main operating system for a wide variety of hardware platforms and Gentoo Prefix which resides in a subdirectory underneath another unixish operating system such as Mac OS X.
In addition to great number of official ebuilds in the main Portage tree, many more ebuilds can be found in overlays. We contribute to some of them: