The most notable of these implementations is the Gentoo/Free BSD project.
There is an ongoing effort called the Package Manager Specification project (PMS) to standardise and document the behaviour of Portage, allowing the ebuild tree and Gentoo system packages to be used with alternative package managers such as Paludis and pkgcore.
The emerge command can also be used to download and install precompiled binary files.
The Portage system offers the use of "USE flags", which allows users to indicate which software features they would like to include (and exclude) while building packages.
USE flags may be set manually, or via user-friendly tools such as 'ufed' (USE flag editor), which lists flags along with their description.
Portage is written in the Python programming language, and is the main utility that defines Gentoo.There are over 19,000 ebuilds available, the majority of which are distributed by the Gentoo mirrors.