Implementation
Since Debian 0.93, a deb file is implemented as an ar archive. Canonical contents of this archive are three files:
- debian-binary: deb format version number. This is "2.0" for current versions of Debian.
- control.tar.gz: all package meta-information. It tells dpkg what to configure when the package is being installed.
- data.tar, data.tar.gz, data.tar.bz2, data.tar.lzma or data.tar.xz: the actual installable files.
The debian-binary file must be the first entry in the archive, otherwise it will not be recognized as a Debian package.
Read more about this topic: Deb (file Format)