Eventing - or horse trials - originally evolved from the training and selection of cavalry horses.

Each of the three disciplines involved in modern day eventing competitions is designed to test the horse's ability.

Dressage demonstrates how trainable the horse is, and allows assessment of its three basic paces: walk, trot and canter.

The cross country tests stamina, speed, jumping and bravery, while the show jumping requires athleticism, control and accuracy. The sport, rather like the pentathlon, combines different disciplines in one competition and is run on a cumulative penalty basis. The competitor with the least penalties at the end is the winner.

The first phase is dressage, which comprises a set sequence of compulsory movements in an arena 20 metres wide and 40 or 60 metres long. The test is assessed by one or more judges who are looking at balance, rhythm and suppleness and most importantly, obedience of the horse and harmony with the rider. Each movement is scored out of ten with the total being added up and converted to a penalty score in a percentage.

The show jumping phase is one round of jumping with a maximum time allowed. The objective is to jump all the fences clear inside the time. The fences are not as high as in top level show jumping, but are quite substantial especially for horses whose particular strength lies in other phases. Fences knocked down and refusals to jump incur penalties, as does exceeding the time allowed.

The third and final phase is the cross-country in which a course of fixed natural obstacles has to be jumped, again inside a specified time. Going over the time allowed incurs penalties; being well under it is of no benefit and can unnecessarily tire the horse. Stopping at obstacles or a rider fall also incurs penalties.

Horses progress through the levels as they score points and gain experience. Competition levels are as follows: