Application

• The bit is placed inside the horse's mouth, where it will push down on the tongue, as well as the "bars", or spaces between the teeth, where the pressure will be administered. Sometimes a bit may also push against the roof of the mouth.
  
  

Function

• A bit functions by putting pressure on the horse's mouth, which, often in conjunction with a bridle which adds pressure to other areas of the horse's head, necessitates the animal move where the handler is leading them to alleviate the unpleasantness.
  
  

The Snaffle

• A snaffle is one of the three common varieties of bit which does not have shanks and applies the same pressure as the handler exerts on the reins.
  
  

The Curb

• A curb is a bit with shanks, or a sort of lever, that has a strap beneath the jaw and acts in concert with the mouthpiece to put pressure on the bars, tongue and jaw. How much pressure applied is determined both by what the handler exerts on the reins and the length of the shank, with a longer shank giving more pressure. This type of bit has more pressure than the snaffle and requires caution, as a harsh tug can be extremely unpleasant to the animal.
  
  

The Gag

• The third type of commonly used bit, the gag, exerts pressure on lips of the horse by pushing up in the mouth, and is similar to the snaffle in that it has no shanks. However, a gag with shanks is available, both working on the lips and performing the functions of the curb bit. This type of bit raises a horse's head and is somewhat controversial, having been abandoned by some trainers.
  
  

Prevention/Solution

• Using a bit incorrectly can lead to problems such as your horse chewing on or trying to escape the bit, dry mouth and extreme pain. Frequently, this is caused by the handler pulling too hard or quickly on the reins and can be solved by teaching the horse to react to a gentler tug. An improper fit is another problem, which can cause sores in the horse's mouth and requires finding another bit or using a bit guard to solve. Some horses simply don't like a particular type and therefore won't respond to it.