Portage is a package management system originally created for and used by Gentoo Linux and also by ChromeOS, Calculate, Sabayon, and Funtoo Linux among others. Portage is based on the concept of ports collections. Gentoo is sometimes referred to as a meta-distribution due to the extreme flexibility of Portage, which makes it operating-system-independent. The Gentoo/Alt project was concerned with using Portage to manage other operating systems, such as BSDs, macOS and Solaris. The most notable of these implementations is the Gentoo/FreeBSD project.

There is an ongoing effort called the Package Manager Specification project (PMS), which aims 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. Its goal is to specify the exact set of features and behaviour of package managers and ebuilds, serving as an authoritative reference for Portage.