The house mouse (Mus musculus) is a small mammal of the order Rodentia, characteristically having a pointed snout, small rounded ears, and a long naked or almost hairless tail. It is one of the most numerous species of the genus Mus. Although a wild animal, the house mouse mainly lives in association with humans.
The house mouse has been domesticated as the pet or fancy mouse, and as the laboratory mouse, which is one of the most important model organisms in biology and medicine. It is by far the animal most commonly genetically altered for scientific research.
House mice have an adult body length (nose to base of tail) of 3.0–3.9 in and a tail length of .0–3.9 in. The weight is typically 0.4–0.9 oz. In the wild they vary in color from light to dark brown but domesticated fancy mice and laboratory mice are produced in many colors ranging from white to champagne to black.
They have short hair and a some, but not all, sub-species have a light belly. The ears and tail have little hair. The hind feet are short compared to Apodemus mice; the normal gait is a run with a stride of about 1.8 in, though they can jump vertically up to 18 in.
The voice is a high-pitched squeak. House mice thrive under a variety of conditions: they are found in and around homes and commercial structures, as well as in open fields and agricultural lands.