Simplify the following text for a Grade 4 native English-speaking person.
Original: `` True rats '' are members of the genus Rattus , the most important of which to humans are the black rat , Rattus rattus , and the brown rat , Rattus norvegicus . Many members of other rodent genera and families are also referred to as rats , and share many characteristics with true rats .
Simplified: Most rats are in the genus Rattus .