Portage
From Gentoo Linux Wiki
Portage is the package management system for Gentoo, and is based off of BSD's ports system.
When instructed by the user via the emerge command, Portage automatically fetches and compiles software, including all dependencies, from scratch. Portage's main configuration file is /etc/make.conf; its tree is located at /usr/portage; and it downloads its files to /usr/portage/distfiles.
For a description of the hierarchy of ebuilds Portage uses to build and install packages, see the article on the Portage tree.
