Translation(s): English - Italiano - Português - Português (Brasil)
The Debian Free Software Guidelines (DFSG) is a part of the Debian SocialContract. An incomplete collection of DFSG-compatible licenses is at DFSGLicenses.
Debian Policy 6.7.8.2. Repackaged upstream source describes when and why Debian packages are repackaged to fit DFSG, rather than shipping a pristine source tarball.
The uscan utility (from the Debian devscripts package) and gbp import-orig (from the git-buildpackage package) may be used to create DFSG source tarballs.