An armrest is a padded or shaped support where you rest your arm while sitting. You'll find armrests on car seats, airplane seats, movie theater chairs, and many sofas and recliners. They stick out from the sides of the seat at just the right height so your elbow and forearm can relax comfortably instead of hanging in the air or pressing awkwardly against your body.

Armrests make long periods of sitting much more comfortable. On a long car trip, you can rest one arm on the armrest between the front seats. In an airplane, the armrests can become surprisingly important: when two passengers are squeezed into neighboring seats, they sometimes have to figure out how to share that middle armrest fairly.

Some armrests fold up or down, and fancier ones might have controls built into them for adjusting the seat or storing small items like TV remotes.