Silks are the way horse owners and barns represent. Each owner or stable has a particular set of silks they use for each and every horse they own. This is for those handicappers (betters) out there that swear a horse to win by the stable or the simple fans looking for their favorite barn.
One of my favorite silks is those for West Point Thoroughbreds. I'm not sure why I find their silks so appealing, but I know when I see that black star on the gold torso, I should be keeping my eye on that horse.
Although silks show where the horse hails from, it also is a easy way for spectators to keep their eye and the horse they bet on. The vibrant colors are usually unique to one or two horses in a race, and help the onlookers keep track of where their horse is running. Silks can be seen from the highest seat and from across the track due to their normally bold colors and patterns. Trust me, this comes in handy when watching the Derby which sports a twenty horse field.
Silks are very useful and an important part of racing. Should you want to give designing them yourself, try this link and make your own silks! If you like them you can even buy them!