1. Territorial consciousness: Cats are animals with strong territorial consciousness. They may mark territory boundaries at home or warn other cats to leave their territory.

2. Seek asylum: Cats may seek asylum at home because they feel safe and warm.

3. Looking forward to entering the room: The cat may want to enter the room because it provides more security and comfort.

4. Wait for the owner to go home: The cat may wait for the owner to go home at the door because it expects the owner's companionship and care.

To determine the specific reason, you can observe the behavior and expression of the cat. If the cat is alert and looks around, it may be marking the territory; If the cat is close and wants to enter the house, it may be seeking asylum or looking forward to entering the house; If the cat has been waiting for its master to come home, it may want his master's company.