The breed standards for the Papillon is different in many countries however all are similar. Below we are specifically talking about the UK Kennel clubs breed standard for the Papillon - taken from the UK Kennel Club website.
Dainty, well balanced little dog. An alert bearing and intelligent expression.
The name ‘Papillon’ is derived from the shape and position of the ears. When erect they are carried obliquely like the spread wings of a butterfly, hence the name. When the ears are completely dropped this type is known as the ‘Phalene’ (Moth). Head markings should be symmetrical, about a narrow white, clearly defined blaze which is desirable but not essential to represent the body of a butterfly.
Lively, intelligent, friendly, with no aggression; always alert.
Head and Skull
Skull slightly rounded between ears, muzzle finely pointed and abruptly finer than the skull, accentuating well defined stop. Length from tip of nose to stop approximately one-third of length of head. Nose black.
Medium size, rounded, never bulging, dark with dark rims, placed rather low in skull.
Very large, mobile with rounded tips, heavily fringed; set towards back of head far enough apart to show slightly rounded shape of skull. Leathers firm but fine. When erect each ear should form an angle of approximately 45 degrees to head.
Jaws strong, with perfect regular, and complete scissor bite, i.e. upper teeth closely overlapping lower teeth and set square to the jaws. Lips thin, tight and dark in colour.
Shoulders well developed and sloping. Chest rather deep. Forelegs straight, slender with strong, fine bone. Elbows close to chest.
Fairly long with level topline; well sprung ribs, loin strong, of good length, slightly arched belly.
Well developed, well turned stifle. Legs when viewed from behind parallel.
Fine, fairly long, hare-like. Tufts of hair between toes extending far beyond them.
Long, well fringed, set on high, arched over back with fringes falling to side to form plume.
Light, free-flowing, positive and free from any restriction. Viewed from in front or behind, legs and feet moving parallel to each other, with feet turning neither in nor out. Viewed from side, dog covering ground well with no hint of hackneyed action.
Abundant, flowing but without undercoat; long fine silky, falling flat on back and sides; profuse frill on chest; short and close on skull, muzzle and front parts of legs. Rear of forelegs to pasterns, tail and thighs covered with long hair.
White with patches, which may be any colour except liver. Tricolours, black and white with tan spots over eyes, tan inside ears, on cheeks, and under root of tail.
Height 20-28 cms (8-11 ins). Dog will appear slightly longer than high when properly furnished with ruff and hind fringes.