Although there are hundreds of design variations, the basic families of bits are defined by the way in which they use or do not use leverage. They include:
Direct pressure bits without leverage:
Snaffle bit: Uses a bit ring at the mouthpiece to apply direct pressure on the bars, tongue and corner of the mouth.
Curb bit: A bit that uses a type of lever called a shank that puts pressure not only on the mouth, but also on the poll and chin groove.
Pelham bit: A single curb bit with two sets of reins attached to rings at the mouthpiece and end of the shank. Partly combines snaffle and curb pressure.
Kimblewick or Kimberwi >Bit combinations
A type of bridle that carries two bits, a bradoon and a curb, and is ridden with two sets of reins is called a Weymouth or double bridle, after the customary use of the Weymouth-style curb bit in a double bridle.
Non-curb leverage designs:
Gag bit: A bit that, depending on design, may outwardly resemble a snaffle or a curb, but with added slots or rings that provide leverage by sliding the bit up in the horse's mouth, a very severe design.
Bits are further described by the style of mouthpiece that goes inside the horse's mouth as well as by the type of bit ring or bit shank that is outside the mouth, to which the reins are attached.
Types of headgear for horses that exert control with a noseband rather than a bit are usually called hackamores, though the term "bitless bridle" has become a popular colloquialism in recent years.
For a more descriptive page about bits please click here