When something is checked, it means it has been examined or inspected to make sure it's correct, safe, or in good condition. Before a pilot takes off, the plane's systems get checked for safety. When you finish a math problem, you might go back and check your work to catch any mistakes. A doctor checks your heart rate and temperature during a checkup.

The word also means marked with a small symbol (usually a ✓) to show completion or selection. When you finish items on your to-do list, you might put a check mark next to each one. On a multiple choice test, you check the box next to your answer.

Checked can also describe a pattern of squares, like a checkered floor or a checked tablecloth. Checkerboards have this pattern, which is where they get their name.

In sports like hockey, checking means using your body to block or stop an opponent, though this is a different sense of the word.

The phrase check in on someone means to see how they're doing: you might check in on a friend who's been sick. When you keep something in check, you're keeping it under control, like a general who keeps the enemy forces in check.