Often referred to as the ‘parade ring’, the paddock is where the horses running in the forthcoming race are paraded for racegoers to get a proper look at the field. It is also to get the animals moving and more relaxed in a frantic environment. The ‘pre-parade ring’ is effectively the same but is hidden somewhere out of sight of the cameras and the horses are not kitted out with their racing equipment etc.
You may here a term like ‘paddock pick’ from time to time. This is essentially someone with knowledge (supposedly) assessing a horse’s movement and demeanour in the parade ring. If they are judged to be moving well, then this is a good thing. If a horse becomes sweaty, or noticeably anxious, then this is deemed negative to its chances of winning.
When talking in the context of a racecourse, this is where the horses are kept before and after races. It is here where a vet will assess them for pre and post race injuries. They will also eat and drink according to trainer instruction. The paddock is the last place that the horse will be in away from the gaze of the racegoers, and as such is usually the last place where they are calm.