Bats are often considered to be pests, and for good reason. They can carry a number of diseases, including rabies, and their droppings can contaminate food and spread disease. But just because you see one bat in your house doesn't necessarily mean there are more.
There are a number of reasons why bats might enter homes. They may be looking for a place to roost or nest, or they may be seeking shelter from the cold. Bats are also attracted to areas where there is food available, so if you have a problem with insects in your home, that could be another reason why bats are coming inside.
If you do find a bat in your home, it's important to take precautions. Don't try to catch or kill the bat yourself - instead, contact your local animal control or wildlife agency for assistance. And if you have any questions about rabies exposure, please call your doctor or health department immediately.