Locking your luggage is a good way to deter casual thieves. These people are likely to move on to another bag that's not protected if they can't easily access the items inside yours. However, determined thieves can break through most luggage locks. For your protection, it's a good idea to keep valuable items, such as jewelry and electronics, in your carry-on bags instead of your checked luggage. While you might also lock your luggage if you have a lock, you shouldn't rely on it for your security.