The playing field is 120-yd (110 m) long and 53.3-yd (48.8 m) wide. At each end of the 100-yd main body of the playing field, white lines called goal lines mark off the entrances to the end zones. Each team defends one end zone and must carry or pass the ball into the opponent's 10-yd (9-m) end zone to score. Lines parallel to the end zones cross the field at 5-yd (4.5-m) intervals. Centered on the back line of each end zone are goalposts, consisting of a 10-ft (3-m) vertical pole topped by a horizontal crossbar from which two vertical upright ....