The quarterback (or another offensive player on occasion) lines up directly behind the center to take the snap. Sometimes referred to as standard formation (as opposed to shotgun formation).
Although it sounds like a simple maneuver the smoothness with which the snap occurs can affect the outcome of the play. Centers and quarterbacks practice the snap for hours to make sure their are no mistakes and the process is automatic. Many fumbles occur during the snap because the center fails to get the ball into the hands of the quarterback. Centers sometimes try to fake a snap in order to draw defensive players off sides and draw a penalty. Lining up under center can also make it more difficult for the defense to determine if the play is going to be running or passing in nature.