Scoring
Touchdowns:
7 points are awarded to a team that scores a touchdown. The scoring team can elect to decline the automatic 1 point conversion and attempt a two-point conversion from three paces out. If they are successful in the conversion they are awarded 2 points, making the touchdown and conversion worth 8 points. If they are not successful, they walk away with 6 points instead.
A two-point conversion can be run back by the defense for two points.
A touchdown is scored when an offensive player has control of the ball and has one foot (or the majority of his or her body while in a prone position) in the end zone. As with all all catches, some leeway on whether the player's foot was in bounds is given if the player has completed a "spectacular" catch.
Field goals:
A field goal is worth 3 points. Drop-kicked field goals are worth 6 points. To score a field goal, two defensive players create the shape of an "H" and then each post steps two paces away from each other. These players are the goalposts.
On any field goal attempt the ball must be hiked from center at the line of scrimmage and must be kicked from the ground, either via a holder or via a drop-kick.
No rushing is allowed against a field goal attempt and no fake field goals are allowed. The play is off the clock. The ball cannot be advanced by either team, even if blocked or short. The ball can be held (or dropped-kicked) from anywhere behind the line the scrimmage.
On drop-kick attempts, the defense may attempt to block the kick but only from their side of the line of scrimmage.
The "goalposts"
Safeties:
a safety is scored when an offensive player is tagged in his or her own end zone or when an offensive player kicks the ball or fumbles the ball out of bounds through his/her own end zone. A safety is worth 2 points for the defensive team and the offense must kickoff to the defense, from their own fifteen yard line.
The "X-point" play:
At the end of the game if one team is losing by more than 8 points, that team is allowed an "X-point play" -- either a final "Hail Mary" pass after their final fourth down (i.e. a "fifth down") or, assuming they have scored a touchdown on the final possession, an "X-point conversion" attempt. Either way, an "X-point play" is worth however many points it takes to tie the game. Teams that are down by 8 points or less must try to win or tie the game the old fashioned way however.