A locker is a tall, narrow metal cabinet with a door that locks, used to store personal belongings safely. Most schools have rows of lockers lining the hallways where students keep their books, backpacks, gym clothes, and lunch boxes during the day. Each locker has a lock, either with a key, a combination dial, or a digital code, so only the person assigned to it can open it.

The word comes from the idea of something that locks. Lockers keep your stuff secure while you're in class or at practice. Gyms, swimming pools, and sports stadiums also have lockers where people change clothes and store their things while they exercise or watch games.

Opening a combination locker can be tricky at first: you have to turn the dial to the right numbers in exactly the right sequence, and if you mess up, you have to start over from the beginning. Many students remember the frustration of standing in a crowded hallway, trying to remember their combination while the bell is about to ring. But once you've practiced a few times, opening your locker becomes automatic, and you can grab what you need in seconds.