In football, a punt is when the offensive team kicks the ball to the opposing team, generally on fourth down. The punter is the position responsible for punting on a football team. Punts usually happen on fourth down in order to move the ball further away from the end zone the opposing team is attacking. The process of punting is conducted as a 'special teams' play.
The offensive line gathers at the line of scrimmage and snaps the ball to the punter, who is about 15 yards back. During punts, the punter will typically have blockers in front of him to stop the other team from blocking the punt and gunners to run down field and tackle the punt returner. Once he receives the football from the snap, the punter will take two to three steps, drop the ball and kick it (before it hits the ground) to the opposite end of the field. His goal is to punt the ball as far as possible and with the most hang time, while avoiding kicking it out of bounds. The goal of a punt is to pin the opposing team as far away from the goal line as possible.
A punt is one of four types of kick that can be seen in a football game.
For a punt, players will set up on the line of scrimmage just like any other play. However, the special teams units for both teams will come onto the field in preparation for the punt. At times, teams may ever fake a punt to catch the defense off guard.
The kicking team, or the team that is performing the punt, snaps the ball to the punter. The punter then drops the ball and kicks it in the air (before the ball hits the ground) all in a single motion.
The receiving team awaits the kick and a player called the punt returner will catch the ball and attempt to return the ball as far down the field as possible, without getting tackled. Returns in football are used to determine the starting position of the line of scrimmage. If the punt goes out of bounds, the ball will be placed at the spot it went out at.
A punt typically occurs in a fourth down situation for the offense, perhaps when they have a lot of yards to gain and don't want to risk going for a first down. In this circumstance, the offense would be too close to the end zone they are protecting, so a turnover on downs would be costly and allow the other team an easier scoring opportunity. So instead, they elect to punt the ball down field and away from the end zone their opponent is attacking to help the defense.
If you want to learn more about punts and the special teams, check out the following tutorials: