All horse races fall into one of two categories ? a handicap race or a conditions race, with handicap races far outweighing conditions races at most events.

A handicap is a race where each horse is allocated a different weight according to ability so in theory each horse has an equal chance of winning. The British Horseracing Board (BHB) have handicappers who produce an official rating (the horse's 'mark') for each horse in the UK who qualifies to run in a handicap race. This mark that the handicappers give the horse will be on a sliding scale between 0 and 120. Zero marks would basically be a crippled horse ☹ while three year old horses at the top of the scale would be the horses entering races such as the Derby.

Sometimes horses do run 'out of handicap' which means that the horse will be running in the race at a disadvantage - the trainer will be aware of this, but will still believe that his horse has a chance of winning.

The evaluations are made on a weekly basis and their results stored on computer by Weatherbys, who are horseracings main administrative body, and each time a horse runs in a race it must be decided by the handicapper whether to adjust his rating depending on a good or a bad performance.

While this all sounds confusing, and to be fair, it must be a lot of hard work for the handicappers and Weatherbys, it all basically means: the higher the horses rating, the better he is. However this could also mean that if you are betting on the horse with the highest (best) handicap, you could be betting on the heaviest horse in the race, as each point in the scale is equivalent to one pound (lb) in weight. This means that, for example, a horse with a rating of 45 will carry 10lbs less than a horse in the same race which is rated at 55, and a horse that had been rated 119 on the scale would be 4lbs better than a horse rated 115 by the handicappers. A perfectly handicapped race would be one where all horses crossed the finishing line at exactly the same time, which as we all know doesn't happen ? but it does make things as fair as possible.

There is also a 'weight-for-age' adjustment when horses of differing ages compete against each other in a race, as horses grow through the ages of 3, 4 and 5 years.

Handicaps have different levels, races being classed as A, B, C, D, E, F or G with A being the highest class handicaps and G the bottom class, and the horses official mark will determine which class of race he can be entered into.