The Rat is one of the most well-known rodent. Rats are rodents that resembles a large mouse, typically having a pointed snout and a long, sparsely haired tail. Some kinds have become cosmopolitan and are sometimes responsible for transmitting diseases. Family Muridae: many genera, including Rattus (the Old World rats), and several hundred species. Thought to have originated in northern China, this rodent has now spread to all continents and is the dominant rat in Europe and much of North America. Rats live in close association with people. In urban or suburban areas rats live in and around residences, in cellars, warehouses, stores, docks, and in sewers. On farms rats may inhabit barns, livestock buildings, silos, and beneath concrete slabs. Rats live wherever suitable food, water, and shelter are present. Although rats can climb, rats tend to inhabit the lower floors of multistory buildings.