The Software Commons is the vast body of human knowledge embedded in software source code, that is publicly available and can be freely altered and reused. Free and Open Source Software (FOSS) constitutes the bulk of it. Sadly we seem to be at increasing risk of losing this precious heritage built by the FOSS community over the paste decades: code hosting sites shut down when their popularity decreases, tapes of ancient versions of our toolchain (bit-)rot in basements, etc.
The ambitious goal of the Software Heritage project is to contribute to address this risk, by collecting, preserving, and sharing all publicly available software in source code form. Together with its complete VCS development history. Forever, of course.
Although still in Beta, Software Heritage has already archived more than 3 billion unique source code files and 700 million unique commits, spanning more than 50 million FOSS projects from major software development hubs, GNU/Linux distributions, and upstream software collections.