kickstand
A metal bar that holds a parked bike upright.
A kickstand is a metal bar attached to a bicycle or motorcycle that swings down to hold the vehicle upright when parked. When you're ready to ride, you push the kickstand back up with your foot, and it tucks neatly against the frame while you're moving.
Before kickstands, cyclists had to lean their bikes against walls, trees, or fences, which often led to scratched paint or bikes toppling over. The kickstand solved this problem elegantly: a simple piece of metal that deploys in seconds and keeps your bike stable on flat ground.
Most children's bikes come with kickstands, though serious racing bikes often skip them to save weight. When you park your bike, you roll it slightly backward while pressing the kickstand down with your heel, and the bike balances on the stand and rear wheel. It's one of those inventions so practical and simple that once you have one, you wonder how anyone managed without it.