Bits have been used for a very long time to control horses.  The bit is used to communicate the riders desire to the horse via pressure from the rider on the mouth.  The bit can work on different parts of the the horses head and mouth and can produce quite severe pressure on sensitive areas. "severity" ranges from a "mild" snaffle  to curb bits which act on several areas of the horses head and mouth.

Before bits were invented horses were ridden using bitless bridles, which communicated via pressure on the outside of the horses head, usually round the nose.  This type of bitless comunication is becoming popular today as it has been proven that bits cause many problems in the horse.  Here is a shortened list of some of the problems bits can cause.

rearing,bucking,bolting,headshaking,spookiing,agression,hard mouthed,pulling on the bit, difficulty steering,incorrecxt canter leads,muscle cramps,refusing jumps,roaring and gurgling,deformity of the windpipe, asphyxia-induced pulmonary œdemacoughing at exercise,stiff or choppy stride,stumbling,interfering with hind hoof,shortage of oxygen,bone spur formation on the bars of the mouth,lip sarcoids,lacerated or amputated tongue,sharp enamel edges leading to cheek ulcers. (‘bleeding’ or exercise-induced pulmonary haemorrhage),

Riding without a bit removes the dangers and discomfort of the above.  Simple train the horse to pay attention to the communication recieved around the head and not the bit.  Some people (not necessarly you!) think that horses stop because of the pain/discomforrt of the bit on the mouth.  While this may be true, it is not communication!  Pulling hard on the bit and hoping your horse will stop to avoid the pain is not horsemanship, it is bullying and there is no excuse for it. It is also a fight between you and a half tonne horse, no points for guessing who will win!

 Any cue can be taught for the horse to stop, and a well trained horse will stop.  For exmple, lifting the reins, voice aids, touching the horses shoulder,weight aids,  even something as silly as touching the horses ears can be taught as a cue for stop!  So the bit is not even necessary for stopping a horse.  Pulling on a bit doesnt make the horses legs stop moving, if the horse wants to run off whilst you are pulling at his mouth, he can!   It would be like someone pulling at you hair whilst you are running, it might be annoying but you can still move.  Bits dont stop horses, horses brains stop horses.  You need to communicate to the horse and get him to think about stopping,turning ect, this can be done safely without a bit.

Horses do not like bits.  Anyone who thinks they do is mistaken!  Many horses clamp their mouths down at the site of a bit and need convincing to open them.  Signs of stress accociated with the bit are, avoiding the bit, head in front or behind the bit, tongue over the bit, chomping at the bit, opening the mouth, leaning on the bit, pulling, running off, head shaking, reluctance to be ridden, foaming at the mouth when ridden.  Why anyone would think a prey animal would like having a piece of cold metal in their mouths, for a preditor to yank about needs to rethink it.  Horses do not cry out in pain, if they did people would think differently.  People dont walk their dogs with bits, horses dont need them either.  I've heard people comment that when a horse is foaming at the mouth it means the horse is relaxed.  This isn't true.  A horse foaming at the mouth is usually distressed by the bit.  Do you ever see horses foaming at the mouth in the field because they are "relaxed"?   Foaming means the bit is interfering with both breathing and swallowing, perhaps due to obstacles for the horse's tongue position, causing the horse to push air into its saliva rather than swallowing the saliva.  Next time you are at a show, see how many horses are running round with their mouths open, or have got thier mouths strapped tightly with a flassh to hide the fact that their horse is distressed.A lot of people use flash nosebands to force the horse to keep his mouth closed when he is opening it.  This doesnt solve the problem, it just makes the horse unable to escape the discomfort and makes him feel more miserable.

If you plan on "going bitless" there are many different types of bitless bridle on the market.  I plan on reviewing them on this site soon.  I wouldnt advise just putting a bitless bridle on and expecting your horse to be perfect first time, most likely your horse will be relieved or confused by the lack of bit the first time.  Some might  go a bit faster than normal at first as they feel less restricted.  This happened with one of my horses and lasted a few minurtes.  Others might act as if they've had a bitless bridle all their lives.  Both my horses are more controllable in a bitless than with a bit.  One runs from a bit and bolts, the other ignores a bit and will argue with it.   With a bitless bridle my ignorant pony will work "on the bit" do gallop to halt transitions and is gererally a pleasure to ride.   The one who bolts with a bit is now more laid back (lazy even) which I prefer to being bolted off with a 40 miles an hour with her head in the air!
 I recommend getting your horse used to a bitless in a safe area for the first few times until you are confident your horse is controlable.  Dont be tempted to cling onto your horses head with the reins.  This is the instinct you get when you first go bitless!  Let your reins be long.  Allowing your horse to lower his head keeps him calm and less likely to run off.  Pulling on the reins, lifts his head and engages his hindquarters, which means he is ready to run!
If you arent confident to ride in a bitless bridle, maybe have some lessons on  your horse from a bitless instructor!  see the following link.  http://www.bitlessbridle.co.uk/bitless-bridle-uk-bbi.php


Bit vs. Bitless, The CHA Experiment
In October, 2008, at the Certified Horsemanship Association's International Conference, Dr. Cook conducted a unique experiment.  It demonstrated that the performance of four horses immediately and significantly improved, within four minutes, when their jointed snaffle bridle was replaced with a crossunder bitless bridle. Four riding school horses that were being ridden in a crossunder bitless bridle for the very first time, completed two four-minute exercise tests, first in a snaffle bridle, then in the BitlessBridle.   Follow the link. http://www.bitlessbridle.com/ecom/sp?dbID=420