ID is important even for pets who live mainly indoors. That way if they were to escape or get outside, they would be quickly found and returned. If a pet isn’t used to wearing a collar, you may need to train them to get comfortable with the feeling. Positive training—providing treats when they wear the collar—can help them to adjust. You may not have your mostly indoor pets wear collars all the time, but it may be a good idea when they’re hanging out on the deck or when the door is opening and closing regularly, like at a party or event.