The system is based on the Elo ranking system which is used by the World Chess Federation (FIDE) to rank the best chess players. The system has been adapted to rank national teams in soccer and teams in Ice Hockey, American Football and Basketball. The official FIFA rankings for Women's soccer uses the Elo system. More information about the Elo ranking system can be found on Wikipedia.

Frequently Asked Questions:

• Are All-Ireland Championship more important than other matches? Of course. We use a weighting system that gives more importance to All-Ireland matches, then National League matches and then to other competitions like the Walsh Cup and the McKenna Cup.
• Why is team X ranked below team Y despite beating them? The system uses a points rating system to rank teams. It means that regular good results will lead to improved ranking but not freak results. So Donegal Footballers' strong run in the 2007 NFL has more effect than Sligo's two wins to capture the 2007 Connacht SFC.