Rat habitats vary from species to species but typically, they will live in a few different locations.
Terrestrial or arboreal by nature, rats can be found dwelling in burrows or trees. The Norway rat usually makes its home close to the ground. They will burrow near the foundation of homes, or under shrubs and plants near homes. They will often infest through entrances in the basement or garage, places close to the ground.
Roof rats are the opposite, choosing to nest in trees or high places above ground. They can be found in your home in the ceiling or attic or nestled in the eaves. Roof rats will enter through window screens or attic vents that have holes greater than a quarter of an inch in size.
Once rats are in your home, they will nest in walls or areas where they can build a safe place to raise their young. Since all rats are prolific breeders, an infestation can occur quickly once rats find their way in and create a habitat for themselves.
Rats don't always remain in their prescribed habitats. Roof rats can be found near the ground and Norway rats can be found in higher places, but typically, they will find areas to live where they feel are the safest.
Rats use nesting materials such as cardboard or plant materials outside to line their nests and they will maintain outdoor burrows with these materials, as well to keep themselves warm and dry. Rats will also nest near food and water sources, so that is the main reason they live in close proximity to humans. Humans provide food in the form of garbage waste and grains found in pantries, as well as a safe indoor environment. With all these benefits, it's easy to see why rats prefer living with humans.