Chestnut: it is a reddish color and no black points as you see in the picture there can be markings. There are different kinds of chestnut like bright chestnut
Black: this horse must be a definite black with absolutely no trace of brown. the body of the horse is completely black( except for any markings on the face and\or legs). there can be white markings on the face and or the legs.
Brown: the body is a mixture of black and brown hair, with dark brown mane and tail.
Gray: their skin is dark grey and there coat has black and white hairs. gray horses are born dark and do lighten with age. there are different kinds of gray: light gray which appears white, flea bitten which is when a white coat has dark specks like freckles like in the picture, iron which is a very dark gray coat; and dappled, has dark rings on a gray coat.
Cream: the skin is pale white, and the coat coloring also a cream color, with the mane and tail a cream also. it is possible to have( but quite rare) white leg and face markings.
Skewbald: this horse as patches colored white and can be any color except black. the skin pigment color under the white hairs is pink and the mane and tail are actually two colors the mane is the same color as the neck ( meaning it is black where black and white where white on the neck) and the tail can be black and white( as shone in the picture) or very dark brown.