[horse's gaits] now we know

From Wiki [abridged]:

Walk

The walk is a four-beat gait that averages about 4 mph. When walking, a horse's legs follow this sequence: left hind leg, left front leg, right hind leg, right front leg, in a regular 1-2-3-4 beat. At the walk, the horse will always have one foot raised and the other three feet on the ground, save for a brief moment when weight is being transferred from one foot to another.

Trot

The trot is a two-beat gait that averages about 8 mph, or roughly the speed a human can run. A very slow trot is sometimes referred to as a jog. An extremely fast trot has no special name. In this gait, the horse moves its legs in unison in diagonal pairs. From the standpoint of the balance of the horse, this is a very stable gait, and the horse need not make major balancing motions with its head and neck.

The trot is the working gait for a horse and is the main way horses travel quickly from one place to the next, sometimes for hours.

Canter

The canter is a controlled, three-beat gait that usually is a bit faster than the average trot, but slower than the gallop. Listening to a horse canter, one can usually hear the three beats as though a drum had been struck three times in succession. Then there is a rest, and immediately afterwards the three-beat occurs again. The faster the horse is moving, the longer the suspension time between the three beats.

In the canter, one of the horse's rear legs – the right rear leg, for example – propels the horse forward. During this beat, the horse is supported only on that single leg while the remaining three legs are moving forward. On the next beat the horse catches itself on the left rear and right front legs while the other hind leg is still momentarily on the ground. On the third beat, the horse catches itself on the left front leg while the diagonal pair is momentarily still in contact with the ground.

Gallop

The gallop is very much like the canter, except that it is faster, more ground-covering, and the three-beat canter changes to a four-beat gait. It is the fastest gait of the horse, averaging about 25 to 30 miles per hour, and in the wild is used when the animal needed to flee from predators or simply cover short distances quickly. Horses seldom will gallop more than a mile or two before they need to rest, though at a moderately-paced gallop can sustain it for longer distances before they become winded and have to slow down.

Like a canter, the horse will strike off with its non-leading hind foot; but the second stage of the canter becomes, in the gallop, the second and third stages because the inside hind foot hits the ground a split second before the outside front foot. Then both gaits end with the striking off of the leading leg, followed by a moment of suspension when all four feet are off the ground. A careful listener or observer can tell an extended canter from a gallop by the presence of the fourth beat.