Software List: Categories
GUIs
In this section are general purpose interfaces that can be used with different chess engines. The most popular protocol for the engines is the UCI (Universal Chess Interface) protocol, followed by winboard (also known as Xboard). Chessbase uses a closed protocol that can only be used in its own interfaces. To be included here it must be possible to use the interface for analysis as well as playing a game, and it must have PGN (Portable Game Notation) support for storing and loading games.
Engines
The engines here are mostly UCI engines, with a couple of notable winboard ones. They can be used with all the programs in the GUIs section, and also with some of the programs in the other sections.
Playing
The main use for these programs is as a partner for playing against. They are stand-alone programs that don't require you to download and install additional engines.
Database
In this section the programs are primarily for replaying games, rather than playing against, and so all are capable PGN readers.
Training
A couple of programs to help you improve your play.
Internet
Software for playing against human players on the internet.
Miscellaneous
Finally a small section for programs that didn't fit into the above categories!