Debian is the universal Operating System. So flexible that many users find it too complex.
A Debian Pure Blend is a subset of Debian, simplifying the choices needed. Being "pure" means it is not just "based on Debian" with add-ons, but consists only of Debian.
This talk explains why Debian Pure Blends is the best way to customize a system, and how you can help create one optimized for your own needs.