Rats come into your house in search of food and water and warmth.
If you have food out or even crumbs on the floor or counter then the rats can come into your house and will return if they do find food or any crumbs etc in your house.
If you have dog food or cat food out you should put it up at night when the dog or cat is not eating the food to keep rats out of it.
Store dog or cat food in sealed containers out of your house if possible in a separate shed or garage.
Make sure to keep trash and other debris such as leaves, brush etc clear as rats love to hide in those areas.
Set our rat traps or rat poison to get rid of the rats because they can chew through wires and many other things as well and cause fires.
If rats have gotten into your food you need to throw it out because you can get diseases from the rats.
Keep foods such as rice, beans etc in metal or ceramic containers that are sealed.