Rats are various medium-sized, long tailed rodents of the superfamily muroidea. "Real rat" is a member of the rat genus, and the most important ones for human beings are black rat (rat) and brown rat (rat). Many members of other rodent genera and families are also called rats, which have many characteristics with real rats.

Rats are usually distinguished from mice by size. Generally, when a large rodent like rodent is found, its common name includes the word "mouse" and, if smaller, the word "mouse". The steroid family is extensive and complex, and the two commonly used terms mouse and mouse are not specific in taxonomy. Scientifically, these terms are not limited to rats and members of the genus Rattus, such as the rat and the cotton rat.