I've wondered this for decades but just now decided to look it up. Here is what wikipedia says:
http://en.wikipedia.org/wiki/Official_(American_football)#Positions_and_responsibilities
Positions and responsibilities
The NFL and College Football primary use a seven-official system.
[edit]
http://forum.therx.com/
Referee
A referee (R) is responsible for the general supervision of the game and has the final authority on all rulings. Thus, this position is sometimes referred to as head referee. He can be identified by his white cap, while the other officials wear black ones.
During each play from scrimmage, the referee positions himself behind the offensive team, favoring the right side (if the quarterback is a right-handed passer).
On passing plays, he primarily focuses on the quarterback and defenders approaching him. The referee rules on possible roughing the passer and, if the quarterback loses the ball, determines whether it is a fumble or an incomplete pass.
On running plays, the referee observes the quarterback during and after he hands off the ball to the running back, remaining with him until the action has cleared just in case it is really a play action pass or some other trick passing play. Afterwards, the Referee then checks the running back and the contact behind him.
During punts and field goals, the referee observes the kicker (and holder) and any contact made by defenders approaching them.
In College Football, the NFL and other professional leagues, and in some high school games, the referee announces penalties and the numbers of the players committing them (college and professional), and clarifies complex and/or unusual rulings over a wireless microphone to both fans and the media, including the result of instant replay reviews.
In addition to the general equipment listed above, the referee also carries a coin in order to conduct the pregame coin toss.
[edit]
http://forum.therx.com/
Umpire
The umpire (U) stands behind the defensive line and linebackers, observing the blocks by the offensive line and defenders trying to ward off those blocks – looking for holding or illegal blocks.
During passing plays, he moves forward towards the line of scrimmage as the play develops in order to (1) penalize any offensive linemen who move illegally downfield before the pass is thrown or (2) penalize the quarterback for throwing the ball when beyond the original line of scrimmage. He also assists on ruling incomplete passes when the ball is thrown short.
[edit]
http://forum.therx.com/
Head Linesman
The head linesman (H or HL) stands at one end of the line of scrimmage (usually the side opposite the press box), looking for possible offsides, encroachment and other penalties before the snap. As the play develops, he is responsible for judging the action near his sideline, including whether a player is out of bounds. During the start of passing plays, he is responsible to watch the receivers near his sideline to a point 5-7 yards beyond the line of scrimmage.
He marks the forward progress of the ball and is in charge of the chain crew in regard to its duties. In addition to the general equipment listed above, the head linesman also carries a chain clip that is used by the chain crew in order to properly place the chains and ensure an accurate spot when measuring for a first down.
[edit]
http://forum.therx.com/
Line Judge
The line judge (L or LJ) assists the head linesman at the other end of the line of scrimmage, looking for possible offsides, encroachment and other penalties before the snap. As the play develops, he is responsible for the action near his sideline, including whether a player is out of bounds.
During the start of passing plays, he is responsible to watch the receivers near his sideline to a point 5-7 yards beyond the line of scrimmage. Afterwards, he moves back towards the line of scrimmage, ruling if a pass is forward, a lateral, or if it is illegally thrown beyond the line of scrimmage.
On punts and field goal attempts, the line judge also determines whether the kick is made from behind the line of scrimmage.
In high school (four-man crews) and minor leagues, the line judge is the official timekeeper of the game. In the NFL, college and other levels of football where the official time is kept on the stadium scoreboard clock, the line judge becomes the backup timekeeper.
[edit]
http://forum.therx.com/
Field Judge
The field judge (F or FJ) works downfield behind the defensive secondary on the same sideline as the line judge. He makes decisions near the sideline on his side of field, judging the action of nearby running backs, receivers and defenders. He rules on pass interference, illegal blocks downfield, and incompete passes.
With the back judge, he rules whether field goal attempts are successful.
[edit]
http://forum.therx.com/
Side Judge
The side judge (S or SJ) works downfield behind the defensive secondary on the same sideline as the head linesman. Like the field judge, he makes decisions near the sideline on his side of field, judging the action of nearby running backs, receivers and defenders. He rules on pass interference, illegal blocks downfield, and incompete passes. During field goal attempts he serves as a second umpire.
In college football, the side judge is responsible for either the game clock or the play clock, which are operated by an assistant under his direction.
[edit]
http://forum.therx.com/
Back Judge
The back judge (B or BJ) stands deep behind the defensive secondary in the middle of the field, judging the action of nearby running backs, receivers (primarily the tight ends) and nearby defenders. He rules on pass interference, illegal blocks downfield, and incompete passes.
With the field judge, he rules whether field goal attempts are successful.
If the official time is kept on the stadium scoreboard clock, the back judge becomes the backup timekeeper. In college football, the back judge is responsible for either the game clock or the play clock, which are operated by an assistant under his direction. In high school (five-man crews), the back judge is the official timekeeper of the game. The back judge is also the keeper of the play clock in high school games, and times the one minute allowed for time outs.
http://en.wikipedia.org/wiki/Official_(American_football)#Positions_and_responsibilities
Positions and responsibilities
The NFL and College Football primary use a seven-official system.
[edit]
http://forum.therx.com/
Referee
A referee (R) is responsible for the general supervision of the game and has the final authority on all rulings. Thus, this position is sometimes referred to as head referee. He can be identified by his white cap, while the other officials wear black ones.
During each play from scrimmage, the referee positions himself behind the offensive team, favoring the right side (if the quarterback is a right-handed passer).
On passing plays, he primarily focuses on the quarterback and defenders approaching him. The referee rules on possible roughing the passer and, if the quarterback loses the ball, determines whether it is a fumble or an incomplete pass.
On running plays, the referee observes the quarterback during and after he hands off the ball to the running back, remaining with him until the action has cleared just in case it is really a play action pass or some other trick passing play. Afterwards, the Referee then checks the running back and the contact behind him.
During punts and field goals, the referee observes the kicker (and holder) and any contact made by defenders approaching them.
In College Football, the NFL and other professional leagues, and in some high school games, the referee announces penalties and the numbers of the players committing them (college and professional), and clarifies complex and/or unusual rulings over a wireless microphone to both fans and the media, including the result of instant replay reviews.
In addition to the general equipment listed above, the referee also carries a coin in order to conduct the pregame coin toss.
[edit]
http://forum.therx.com/
Umpire
The umpire (U) stands behind the defensive line and linebackers, observing the blocks by the offensive line and defenders trying to ward off those blocks – looking for holding or illegal blocks.
During passing plays, he moves forward towards the line of scrimmage as the play develops in order to (1) penalize any offensive linemen who move illegally downfield before the pass is thrown or (2) penalize the quarterback for throwing the ball when beyond the original line of scrimmage. He also assists on ruling incomplete passes when the ball is thrown short.
[edit]
http://forum.therx.com/
Head Linesman
The head linesman (H or HL) stands at one end of the line of scrimmage (usually the side opposite the press box), looking for possible offsides, encroachment and other penalties before the snap. As the play develops, he is responsible for judging the action near his sideline, including whether a player is out of bounds. During the start of passing plays, he is responsible to watch the receivers near his sideline to a point 5-7 yards beyond the line of scrimmage.
He marks the forward progress of the ball and is in charge of the chain crew in regard to its duties. In addition to the general equipment listed above, the head linesman also carries a chain clip that is used by the chain crew in order to properly place the chains and ensure an accurate spot when measuring for a first down.
[edit]
http://forum.therx.com/
Line Judge
The line judge (L or LJ) assists the head linesman at the other end of the line of scrimmage, looking for possible offsides, encroachment and other penalties before the snap. As the play develops, he is responsible for the action near his sideline, including whether a player is out of bounds.
During the start of passing plays, he is responsible to watch the receivers near his sideline to a point 5-7 yards beyond the line of scrimmage. Afterwards, he moves back towards the line of scrimmage, ruling if a pass is forward, a lateral, or if it is illegally thrown beyond the line of scrimmage.
On punts and field goal attempts, the line judge also determines whether the kick is made from behind the line of scrimmage.
In high school (four-man crews) and minor leagues, the line judge is the official timekeeper of the game. In the NFL, college and other levels of football where the official time is kept on the stadium scoreboard clock, the line judge becomes the backup timekeeper.
[edit]
http://forum.therx.com/
Field Judge
The field judge (F or FJ) works downfield behind the defensive secondary on the same sideline as the line judge. He makes decisions near the sideline on his side of field, judging the action of nearby running backs, receivers and defenders. He rules on pass interference, illegal blocks downfield, and incompete passes.
With the back judge, he rules whether field goal attempts are successful.
[edit]
http://forum.therx.com/
Side Judge
The side judge (S or SJ) works downfield behind the defensive secondary on the same sideline as the head linesman. Like the field judge, he makes decisions near the sideline on his side of field, judging the action of nearby running backs, receivers and defenders. He rules on pass interference, illegal blocks downfield, and incompete passes. During field goal attempts he serves as a second umpire.
In college football, the side judge is responsible for either the game clock or the play clock, which are operated by an assistant under his direction.
[edit]
http://forum.therx.com/
Back Judge
The back judge (B or BJ) stands deep behind the defensive secondary in the middle of the field, judging the action of nearby running backs, receivers (primarily the tight ends) and nearby defenders. He rules on pass interference, illegal blocks downfield, and incompete passes.
With the field judge, he rules whether field goal attempts are successful.
If the official time is kept on the stadium scoreboard clock, the back judge becomes the backup timekeeper. In college football, the back judge is responsible for either the game clock or the play clock, which are operated by an assistant under his direction. In high school (five-man crews), the back judge is the official timekeeper of the game. The back judge is also the keeper of the play clock in high school games, and times the one minute allowed for time outs.