Gentoo is a free operating system based on both Linux or FreeBSD that can be automatically optimized and customized for just about any application or need.
Gentoo is for the more experienced Linux users. The building of you own software takes a lot of time, CPU power and it can fail to build. We offer limited support for Gentoo, we can help you with the basics but for the rest you are on your own. If you choose Gentoo prepare to spend a lot of time on your Linux system. The upside to Gentoo is the high amount of freedom you have to choose what you want. Compared to Debian, which chooses default options for it's packages, you can choose yourself what to enable in packages.
The Gentoo site says the following about Gentoo:
Because of its near-unlimited adaptability, we call Gentoo a metadistribution.
What is Portage?
Portage is the heart of Gentoo, and performs many key functions. For one, Portage is the software distribution system for Gentoo. To get the latest software for Gentoo, you type one command:
you@yourServer:~$ emerge --sync
This command tells Portage to update your local "Portage tree" over the Internet. Your local Portage tree contains a complete collection of scripts that can be used by Portage to create and install the latest Gentoo packages. Currently, we have more than 10000 packages in our Portage tree, with updates and new ones being added all the time. Portage is also a package building and installation system. When you want to install a package, you type
you@yourServer:~$ emerge packagename
at which point Portage automatically builds a custom version of the package to your exact specifications, optimizing it for your hardware and ensuring that the optional features in the package that you want are enabled -- and those you don't want aren't. Portage also keeps your system up-to-date. Typing
you@yourServer:~$ emerge -uD world
will ensure that all the packages that you want on your system are updated automatically.