These are list files.
The list files here simply describe what files are contained in each Debian ISO image, in order to help users find which images they might want to download. They are simply text files, compressed to save space and download time.
This Debian image build only includes Free Software where possible. However, many systems include hardware which depends on non-free firmware to function properly so this build also includes those firmware files for those cases. See the Debian Wiki non-free firmware page for more information.
See the Debian CD FAQ for lots more information about Debian CDs and installation.
The images here were put together by the Debian CD team , using debian-cd and other software.