gaits (especially horses)

above: horse pacing; both legs on one side move forward together
seen in harness racing horses like Standarbreds, really rough to ride... modified versions result in the gaited horses' smooth ride!

Gait means the movement of the horse's legs and body. Gaited means a specific kind of movement in certain breeds of horse, very smooth and easy to sit.

Walk:    four beats; left rear... left fore...right rear...right fore
Trot:      two beats; left rear and right fore together... right rear and left fore together
Pace:    two beats; both left legs together...both right legs together (really rough to ride!)
Canter: three beats; left rear... right rear and left fore... right fore (right lead, when turning to the right)
                             or; right rear... left rear and right fore... left fore (left lead, when turning to the left)
Gallop:  four beats (an extended canter) 
                                 left rear... right rear, left fore (not quite together)... right fore (right lead)
                                 right rear... left rear, right fore (not quite together)...left fore (left lead)

Gaited horses such as Tennesee Walkers, Rocky Mountain Horses, Kentucky Mountain horses, Saddlebreds, Paso Finos, Peruvian pasos and others do a gait which is somewhere between a walk and a trot or pace... that's a whole'nother book. (Youtube! Look up those breeds, or just "gaited horses").   

Above: horse trotting. Note how diagonal pairs of legs move together. Moment of suspension (left) as left fore and right rear come forward, another moment of suspension occurs later as the other pair comes forward.
Horse cantering: 1. left rear on the ground...2. diagonal pair on the ground...3. right fore on the ground...4. note the moment of suspension as all four legs come off the ground.