A black horse, has a solid black coat with a black mane and tail. If a black horse has brown hairs or even a single white spot, the horse is not truely black.
But the horse is allowed to have white leg markings and, or, face markings.
Bay
A bay colored horse has a brownish black coat with a black mane and tail. These colored horses may have white leg and, or, face markings also. Bays may have black points whether it's on their ears or muzzle or lower part of the legs.
There can be mnay different types of bays like light and dark, and some bays may look more black than anything.
Dark bay or brown
The brown (or dark bay) coat is a mixture of black and brown hairs.
This color coat can have markings boths face and legs.
Chesnut
The chesnut is a reddish brown color, maybe sometimes a bit lighter brown than anything, but this shade of horse has no black points of shades, if so this horse color is not chesnut. The mane and tail can be either a lighter or darker shade then the body color.
This color horse can also have face and, or, leg markings.
Palamino
The palomino coat is gold, with a lighter shade of mane and tail.
This color horse can have different face and, or, leg markings.
Gray
Grey horses have a dark pigmented skin, with grey, and white hairs, sometimes with black. This color horse usually is born with a light coat and has it turn darker as they get older.
As for face markings, grey horses may have a bald face or maybe even a noticible face marking.
Appaloosa
There are various colored paterning coats for appoloosa's; blanket, marble, etc.
since these horses have a white base coat, they don't really have any markings.
Markings
Leg markings
markings from L-R ; cornet band, pastern, sock, stocking.
Snip
Star
Star and strip
Strip
Blaze
Bald face
Dorsel stripe
A black or dark brown stripe that extends from the withers along the backbone.
Wall eye
Usually one of the horses eye's has a blue coloring instead of normal eye color.
This eye is usually common in horses with a bald face or a blaze.