Systems - The most common system used in the UK is ACOL, which together with the equivalent Standard American, now being superceded by the 2/1 club, are both used throughout the world.

There are a large number of other systems, particularly those based on a 'fake' one club or one diamond opening bid, such as Moscito and Precision. One particularly famous system was the Italian 'Roman Club' used with great success about 50 years ago.