Thoroughbreds are really athletic horses, and usally known to be a bit hot. They range from 15.2hh-17hh, and their colors are usally are chestnut, black, bay/brown and occasionaly another color (for example, pinto as you can look it up the new topic).
Thoroughbreds are used as race horses, and they tend to be fast, espically if ever raced. If they raced, but certian to have a vet check (actual it's good to have a pre-purchuse for every horse) because they can have leg inguries.
Thoroughbreds are known for racing (as I said above), eventing, jumpers, hunters, dressage and western (you don't see them too often). However, like any horse they can be used for different disiplines, too. They are fairly versitile, though.
I really like them, though. I think they're more "fragile" then most horses, but that's because of experiences.