The opposing team's kicker punts the ball into or behind the other team's endzone or the opposing team's kick returner kneel in the endzone. This results in the next play starting at the twenty yard line.
Sometimes referred to as "taking a knee" in the endzone
There is a lot of strategy involved in an NFL kick off, which starts the opposing team's offensive drive. The kicker wants to get the ball as close to the opposing team's endzone in order to make the offense drive the farthest distance down the field. Kicking the ball too hard usually results in a touchback, which gives the opposing team the advantage of having the ball on its own twenty yard line. Kicking the ball too short gives the opposing team even better starting field position.