The answer to 'types of rat' is that there are several common species of rats found in homes and buildings. The two most prevalent are the Norway rat and the roof rat.
Norway rats, also known as brown rats or sewer rats, are the larger of the two and typically weigh 12-16 ounces. They have stocky bodies, small ears, and blunt noses. Roof rats, also called black rats or ship rats, are smaller at 5-10 ounces and have slender bodies, large ears, and pointed noses. Both species can cause significant damage by gnawing on electrical wires, insulation, and building materials, as well as contaminating food sources.