Onside Kick
In short
A specialised kick in gridiron football where the kicking team deliberately hits the ball a short distance to try and recover it themselves.
In plain words
Instead of kicking the ball far away, a player kicks it softly so it stays close to their teammates. This allows the kicking team to grab the ball before the other team can get to it.
A simple example
A team is losing by one score late in a match and decides to attempt an onside kick to get the ball back immediately. If a player catches the ball before the opponents, their team keeps possession.
Why it matters
It is a high-risk, high-reward tactic used to change the momentum of a game. While it can help a trailing team score quickly, a failure gives the opponent excellent field position.
Easy to mix up
Do not confuse this with an offside rule violation, which is a penalty for being in an illegal position.