Savannah's website is split into two domain names: savannah.gnu.org for software that is officially part of the GNU Project, and savannah.nongnu.org for all other software.
Unlike SourceForge, Savannah's focus is for hosting free software projects and has very strict hosting policies, including a ban against the use of non-free formats (such as Macromedia Flash) to ensure that only free software is hosted. When registering a project, project submitters have to state which free software license the project uses.
In 2004, after a security compromise and resignations among the Savannah "hackers" (i.e. volunteers) team, FSF announced that it was going to move GNU Savannah from the Savannah (now Savane) software to GForge due to a mistaken perception that the codebase was now unmaintained. The Savannah hackers protested and there's no plan to migrate anymore.
The domain gnu.org attracted at least 9.6 million visitors annually by 2008 according to a Compete.com survey.
The GNU Project's Savannah website started out using SourceForge as its hosting software. However, after Savannah was set up, SourceForge was changed into proprietary software by its authors. The site's administrators at the Free Software Foundation forked the software in order to maintain it.
This software fork was originally called simply Savannah, since it was the software running the GNU Project's Savannah website and had no other name. It was later renamed Savane, the French word for "savannah", to distinguish the software itself from the websites, such as the GNU Project's Savannah, that use the software.