penalties
Video "A Guide to american football"

Penalties
Rule violations are punished with penalties against the offending team. Most penalties result in moving the football towards the offending team's end zone. If the penalty would move the ball more than half the distance to the defense's end zone, the penalty becomes half the distance to the goal instead of its normal value. Most penalties result in replaying the down. Some defensive penalties give the offense an automatic first down. Conversely, some offensive penalties result in the automatic loss of a down. If a penalty gives the offensive team enough yardage to gain a first down, they get a first down, as usual. If a penalty occurs during a play, an official throws a yellow flag near the spot of the foul. When the play ends, the team that did not commit the penalty has the option of accepting the penalty, or declining the penalty and accepting the result of the play.
Loss of down
Illegal scrimmage kick (also loss of 5yards)
Illegally handing ball forward (also loss of 5yards)
Planned loose ball play (also loss of 5yards)
Intentionally throwing backward pass out of bounds (also loss of 5yards)
Illegal forward pass by team A (also loss of 5yards)
Intentionally grounding forward pass
Forward pass illegally touched by player out of bounds
Illegally batting ball (also loss of 15yards) see exceptions
Illegally kicking ball (also loss of 15yards) see exceptions
Loss of 5 yards
Alteration of playing surface for an advantage
Improper numbering or illegal formation
Coin toss infractions
Delay after three timeouts expended
Illegal delay of the game
Advancing a dead ball
Disconcerting offensive signals
Substitution rules infractions
Puting ball in play before declared ready for play
Exceeding 25 second count
Infraction of free kisk formation
Team A blocking during a free kick
Player out of bounds when ball free-kicked
Team A player illegally goes out of bounds (free kick)
Free kick out of bounds (or 30 yard option)
Illegal kick (also loss of down if by Team A)
Team A player illegally goes out of bounds (scrimmage kick)
Taking more than two steps after a fair catch
Illegal snap
Snapper's position and ball adjustment
Team A not within nine yard mark after ready for play
False start or simulation start of a play
Infraction of scrimmage formation
Encroachment (offense) at snap
Player out of bounds when ball is snapped
Offensive player illegally in motion at the snap
Failure to pause full second in shift play
Offside (defense)
Abrupt defensive actions
Interference with opponent or ball
Illegally handing ball forward (also loss of down by Team A)
Planned loose ball play (also loss of down)
Intentionally throwing backward pass out of bounds (also loss of down by Team A)
Player on scrimmage line receiving snap
Illegal forward pass (also loss of down by Team A)
Ineligible receiver downfield
Forward pass illegally touched
Defensive grasping face mask or helmet opening of opponent (also 15 yards)
Running into kicker or holder
Sideline restraining line infraction (also 15 yards)
Interlocked interference or helping runner
Loss of 10 yards
Home team delay
Illegal use of hands or arms (offense)
Holding or obstruction (offense)
Illegal block in the back (offense)
Locked hands
Illegal use of hands (defense)
Holding or obstruction (defense)
Illegal block in the back (defense)
Holding or obstruction (loose ball)
Loss of 15 yards
Marking ball
Numbers changed
Illegal signal devices (also disqualification)
Team not ready to play at start of either half
Simulated substitutions
Interference with opportunity to catch a kick
Illegal block by fair catch signaller
Tackling or blocking fair catcher
Offensive pass interference
Defensive pass interference (first down)
continuous contact to opponent's helmet (first down)
Stricking, kicking, kneeing, elbowing, etc. (first down)
Tripping (first down)
Clipping (first down)
Tackling out of bounds (first down)
Hurdling (first down)
Grasping face mask or helmet opening of opponent (first down) (also five yards)
Offensive grasping of face mask or helmet opening of opponent
Butting or ramming with helmet (first down)
Obviously uncatchable pass (first down)
Roughing the passer (first down)
Top of helmet striking (first down)
Speraring (first down)
Chop blocking (first down)
Blocking below the waist (first down)
Running into opponent out of play (first down)
Stepping on opponent for an advantage (first down)
Illegal contact with snapper (first down)
Leaping (first down)
Blocking a free kicker
Roughing the kicker or holder (first down)
Simulating roughed or run into
Substitute interferes
Illegal participation
sideline restraining line infraction (also five yards)
Obscene or vulgar language
Persons illegally on the field
Player not returning the ball to official
Engendering ill will
Unsportsmanlike conduct
Persons leaving team area
Illegal return of disqualified player
Noise by persons subject to rules
Concealing the ball
Simulated replacements or substitutions
Equipement to confuse opponents
Intentionally contacting an official (also disuqalification)
Defensive restrictions
Illegally batting loose ball (also loss of down)
Illegally batting a backward pass
Batting ball in possession by player in possession
Illegally kicking ball (also loss of down)
Fighting (also disqualification)

Loss of half distance to goal line
Touch Down 6 points. It is scored when a player runs the ball or catches a pass in the opponent's end zone.
After a TD, the scoring team attempts a conversion. The ball is placed on the 2 yard line. If the ball is kicked over the crossbar and through the goal posts it's 1 point. If the team runs the ball or pass it into the End Zone it's 2 points.
A Field Goal worth 3 points, it is scored when the ball is kicked over the crossbar and through the goal posts.
For a safey it's 2 points. A safety is scored by the defense when the offensive player in possession of the ball is forced back into his own end zone and is tackled there or fumbles the ball out of his end zone.
Loss of half distance to goal line
If distance penalty exceeds half the distance (except on defensive pass interference)
Defensive pass interference (if less than a 15 yard penalty) (first down)
Charged timeout for a violation
Not wearing mandatory equipment
Wearing illegal equipment
Head coach's conference
Head coach's challenge
Illegal cleats
Violation
Illegal touching of free kick by kicking team
Illegal touching of scrimmage kick
Scrimmage-kick-batting exception
Disqualification
Prohibited signal devices
Use of tobacco
Flagrant fouls
Two unsportsmanlike fouls
Illegal cleats
Contacting an official
Fighting
Automatic first down (defensive fouls)
Pass interference
Strisking, kicking, kneeing, elbowing, etc.
Piling on
Tripping
Clipping
Hurdling
Tackling out ouf bounds
Facemask defense (15 yards)
Butting or ramming with helmet
Spearing
Running into opponet out of play
Top of helmet striking
Roughing the passe
Tackling receiver of uncatchable pass
Blocking below the waist
Chop blocking
Steppin, jumping or standing on opponent
Continuous contact to opponent's helmet
Illegal contact with snapper
Lepaing
Roughing the kicker or holder
Illegal contact with eligible receiver
Fighting (also diqsqualification)
When-in-question rules
Catch or recovery not completed
Block bellow the waist
Chop block
Block in the back
Ball not touched on kick or forward pass
Ball is accidentally kicked (touched)
Forward pass rather than backward pass
Forward pass and not fumble
It is a catchable forward pass
Stop clock for injured player
Forward progress stopped
Kick-catch interference
Reasonable opportunity to catch
Touchback rather than safety
Twisting, turning or pulling face mask (helmet opening)
Roughing kicker rather than runnin into
Referee's discretion
Penalty for illegal interference
Penalty for unfair acts