Duty is something you're obligated or expected to do, whether because of your role, your promises, or what's right. When a lifeguard is on duty, they're responsible for watching the swimmers and keeping them safe. When a soldier performs their duty, they fulfill the responsibilities that come with serving their country.

Duty often involves doing things even when they're difficult or inconvenient. A student might feel it's their duty to help a struggling classmate understand the homework, or a team captain might see it as their duty to encourage teammates even after a tough loss. Your duties might include walking the dog each morning, cleaning your room, or being honest even when the truth is uncomfortable.

The word carries a sense of honor and commitment. People talk about the call of duty when something important needs doing, or being duty-bound when they feel strongly obligated. A police officer's duties include protecting citizens. A doctor's duties include caring for patients.

When someone says “I'm just doing my duty,” they often mean they're doing what needs to be done without expecting special praise. Duty isn't always fun, but fulfilling your duties is how you earn trust and show others they can count on you.