A custodian is someone who takes care of a building and keeps it clean, safe, and working properly. Schools, offices, and apartment buildings all have custodians who vacuum floors, empty trash cans, fix broken lockers, shovel snow from walkways, and handle hundreds of other tasks that keep the building running smoothly.

Custodians often work early in the morning or late at night when fewer people are around, so you might not always see them, but you'd definitely notice if they stopped doing their job. A good custodian takes pride in keeping things orderly and functional.

The word can also describe anyone who protects or guards something important. A museum might call someone a custodian of historical artifacts, meaning they're responsible for preserving these treasures. Parents are sometimes called custodians of their children's well-being. In this broader sense, a custodian is a guardian or protector, someone entrusted with something valuable who takes that responsibility seriously.