Rattus norvegicus, commonly known as the brown rat or Norway rat, is a species of rodent that is widely distributed around the world. It typically has a robust body, a long tail, and fur that ranges from brown to gray. These rats are highly adaptable and can thrive in various environments, including urban areas, farms, and forests. Brown rats are primarily nocturnal and are known for their intelligence and social behavior. They often live in colonies and communicate through vocalizations and scent markings. Rattus norvegicus plays a significant role in ecosystems but can also be considered pests due to their potential to damage crops and spread diseases.