The brown rat, common rat, Hanover rat, Norway rat, Norwegian rat, or wharf rat (Rattus norvegicus) is one of the best known an most common rats, and also one of the largest. Thought to have originated in northern China, this rodent has now spread to all continents, except Antarctica, and is the dominant rat in Europe and much of North America. It lives wherever humans live, particularly in urban areas. It is a brown or grey rodent, with a body up to 25 cm (10 in) long, with the tail a similar length; the male weighs on average 350 g (12 oz) and the female 250 g (9 oz).