Arena Football is a form of football played in indoor arenas designed for basketball or hockey. It differs from football in the amount of players on each side and smaller dimensions of the playing field.

Arena football is an indoor (obviously), fast-paced version of traditional football. Rules differ slightly from those of the traditional game, due to the smaller setting of an arena. These rule differences include no punting, and the ability to play balls off large end zone nets. Arena football is played professionally throughout the United States in the Arena Football League (AFL).

Score more points than the opposing team.

The rules of arena football are the same as traditional football, with the following exceptions:
Arena football fields are 50 yards long, with 8-yard end zones. A heavily padded wall surrounds the perimeter of the field. Goalpost uprights are 9 feet wide, with a crossbar 15 feet above the playing surface. Rebound nets on both sides of the posts bounce any missed field goals back into the field of play. Balls bounced back into play are live, and can be played. Passes that bounce off the rebound nets also remain live. Teams place eight players on the field, from a roster of 20. Traditionally, all players except the quarterback and kicker play offense and defense. Players aren't counted out of bounds on the sidelines unless they are pushed into a wall. All kick-offs take place from the goal line. Punting is illegal. Drop kick field goals are worth four points during normal play and two points as post-touchdown conversions.

Arena football was conceived by James Foster in 1981, after watching an indoor soccer game. Over the course of the next five years, Foster created comprehensive rules and field specifications. In 1987, the Arena Football League (AFL) held its first season. Throughout the 1990's the AFL grew substantially. In 2000, the AFL formed a developmental league called af2.

Football
Goalpost
Helmet
Padding

Arena football can be an extremely dangerous sport due to the amount of contact between opposing players. As such, a helmet and padding must be worn at all times.

Arena football players must possess great strength, speed and agility. These can be attained through rigorous weight training drills and aerobic exercise.

Drop Kick - form of kicking the football, where the kicker will hold the ball in front of himself, drop it, and then kick

Rebound Net - taught nets on either side of the goalposts, which balls can be played off

http://en.wikipedia.org/wiki/Arena_football