Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rats, Rattus rattus, and the brown rats, Rattus norvegicus. Rats are typically distinguished from mice by their size. Rats nest in high places such as trees, but sometimes in burrows under plants. Indoors, they nest in high places in structures, but sometimes in basements, sewers, or under buildings. Rats eat almost anything, but they prefer fruit, vegetables, and cereal products. Rats gnaw, eat stored food, and transmit disease by droppings, urine, bites, and the fleas as well as mites in their fur.