By SHERMAN WAN
Blast San Francisco Bureau

Attending a daylong Super Bowl party, but haven't a clue as to the differences between a touchdown, first down, touch back or quarterback? Don't fear. Here's a quick, step-by-step guide to understanding professional football.

THE LEAGUE

The NFL is divided into two conferences, the National (NFC) and the American (AFC), and three divisions within each conference. Each division has five teams, for a total of 30 in the league.

The NFL merged with a less successful professional league, the American (AFL) in 1970. Other leagues have challenged the NFL, but have not been successful, including the United States Football League (USFL) and the World League of American Football (WLAF), an NFL-sanctioned off-season league which had some teams in Europe. Both of these leagues no longer exist. There is a minor variation called the Arena Football League that uses different rules, and plays in much smaller, indoor arenas.

Steve Young, the quarterback of the 49ers, started in the USFL before going to Tampa Bay in the NFL, and then eventually to the 49ers.

THE SCHEDULE

The schedule for each team consists of four exhibition (or preseason, as the NFL likes to call them) games and 16 regular season games. If a team makes the playoffs, it may play an additional three or four games, depending if it plays a wild card game (see below), culminating in the championship game, which is known as The Super Bowl. This year, Super Bowl XXXII will be played in San Diego. The game rotates the location each year. The most frequent cities have been New Orleans, Pasadena and Miami. San Francisco has never hosted a Super Bowl.

Back to the schedule. Each team plays its four division rivals twice. So automatically, eight games are division games. The other games are divided between teams in the same conference, and to a lesser degree, teams in the other conference. It's not uncommon for teams from opposing conferences not to have played each other in ten years, or more. The better a team does in a year, the better the teams it will play next year, i.e., the harder its schedule will be (however, the eight division games are mandatory).

THE PLAYOFFS

In each conference, the three division winners make the playoffs. The three teams with the next best records make the playoffs as wild cards. Ties are broken by a complex hierarchy of tiebreakers, starting with head-to-head record between the teams.

In round 1, two wild cards play each other, while the other wild card team plays the division winner with the worst record. The remaining two division winners don't have to play round 1, which is known as getting a "bye."

The team with the overall best record in each conference not only gets the round 1 bye, but also has the privilege of hosting all playoff games at home. So unlike baseball, there is a significant reward for having the best record.

The playoffs continue for two more rounds until only one team from each conference remains. They are crowned the NFC and AFC Champions and meet in the Super Bowl in January.

THE GOAL

The point of the game is, of course, to outscore your opponent. The field is 100 yards long, with a end zone that is 10 yards deep. The field is marked every 10 yards, with a goal line and end zone at each end. An arrow next to each marker indicates the respective sides of the field.

E                                          E
N  G <10 <20 <30 <40 50 40> 30> 20> 10> G  N
D                                          D
Z                                          Z
O                                          O
N  G <10 <20 <30 <40 50 40> 30> 20> 10> G  N
E                                          E

A coin is flipped at the beginning of the game. The team that wins the flip chooses whether to take the ball or give the ball to the other team. If the 49ers win the flip and decide the receive the ball, the other team will line up on the 35-yard line closest to its end zone and kick the football. This is known as the kickoff. The 49ers stand on the far side of the field next to their end zone and try to catch the ball. If someone catches it, he will try to run to the other end zone, or as far as he can before he's stopped, or tackled, by the opposing team. This is known as the kickoff return.

The ball is placed where the returner was stopped. For example, let's say the 49er returner gets as far as the 25-yard line. Now, this is where the play begins. The 25-yard line, or wherever the ball is placed, is known as the "line of scrimmage." The 49ers send out 11 guys and the other team send out its 11 guys to stand on opposite sides of the line of scrimmage, with the ball between them.

The ultimate goal is to move the football into the opponent's end zone. In this case, the 49ers, being on their own 25, must travel 75 yards in order to reach the opponent end zone to score. Of course, you don't have to do it all at once. The team on offense has four chances, called "downs," to advance the ball at least ten yards, either by passing or running. If the offensive team fails to move the ball at least ten yards in four downs, then the defensive team takes over possession of the ball at the line at scrimmage.

In the example above, since the 49er kick returner advanced the ball to the 25-yard line, the 49ers have four chances to move the ball to the 35-yard line. This is known as "1st-and-10" (first down and 10 yards to go). Let's say they gain 13 yards in three downs, so moving the ball from the 25 to the 38. They have moved the ball at least ten yards, so the 49ers are rewarded with a new first down at the 38-yard line. Now, they have four new chances to move the ball at least another ten yards, to at least the 48.

Now, let's say the 49ers manage to move the ball only 6 yards in their next three downs, from their 38 to their 44. Now, it's 4th down and they still have four more yards (4th-and-4) to advance to the 48 if they want to keep the ball. They may elect to try to get the four yards, but this is very risky. If they fail, the defensive team takes over the ball at the line of scrimmage, and they would only need to advance the ball 44 yards to reach the 49er end zone. This is not good stragegy, so most teams will kick, or "punt," the ball to the defensive team. The defensive team tries to catch and run the ball back in the other direction, just like a kickoff. Then, their 11 offensive players come out and try to move the ball against 11 49er defenders in the manner shown above.

Play contines back and forth until a team scores, punts the ball to the other team, or loses possession on 4th down. The offensive team may also lose the ball (a "turnover") if the player holding the ball drops it and a defensive player recovers it. This is known as a "fumble." The defensive team may also catch a pass that was meant for an offensive player. This is known as an "interception."

If a team runs or passes the football into the opponent's end zone, it is awarded a "touchdown" (TD) and is worth 6 points. It then gets the opportunity to score an extra point, known as a "PAT" (Point After Touchdown), if the kicker can kick the football through the goalpost. The team may also try to run or pass the ball into the end zone from the 2-yard line. This is called a "two-point conversion," and is worth two points. Most of the time, teams try (and make) the PAT, so the vast majority of touchdowns are worth 7 total points. However, depending on various factors at the time, such as the score, and time remaining, strategy may dictate that the team try for a two-point conversion instead of a PAT.

If the team cannot get the ball into the end zone but is close enough to try to kick the ball through the goalpost, that is called a "field goal" (FG) and is worth three points. There are no PATs or extra points awarded after an FG.

Game time is divided into halves, with two quarters each. Each quarter is 15 minutes long, for a total "play" time of 60 minutes. In real time, this translates to a "game" time of three hours or more.

THE TEAMS

Each team has a total of 45 players. 11 are on the field at one time. Unlike baseball, basketball, or hockey, since the job functions are so specialized, different players play offense and defense. Players can be substituted and brought back into the game at any time.

In the diagram below, the Xs are defense and the Os are offense:

  X      X     ----- defensive back
    X X X       ----- linebacker
X   X X X X   X   ----- defensive back
     ^
     |---------------------- linemen

     0  <------------------ football/line of scrimmage

     |---------------------- linemen
     V
O   O O O O OO  O   ----- wide receiver    
     O        ----- quarterback
    O  O       ----- running back

The quarterback (QB) is the leader of the offense. He passes the ball to the wide receivers (WR) and hands the ball to the running backs (RB). He may even try to run with the ball himself.

The WRs run routes to elude the defensive players and must time with the QB to catch the ball. WRs are fast and agile.

The RBs take the ball from the QB and try to advance it. This is known as "rushing." They may also catch passes. RBs are also fast, but they must be strong to avoid tackles and have good acceleration.

The linemen's (OL) job is to block the defensive players and open holes so that the RBs have room to run. They also protect the QB from the defensive players who are trying to stop the QB during a pass play. However, the lineman may never touch or carry the ball. Linemen are usually slow, fat, and very strong.

On defense, the linemen (DL) try to reach the QB to stop him from passing the ball. This is known as the "defensive pass rush." If the RB has the ball, they try to stop him. Again, slow, fat, strong.

The duty of linebacker (LB) is, as the name suggests, to back the line. They stop the RB if he gets past the linemen, and are also required to guard or tackle the WR. However, LBs are not as fast as WRs. But they must be strong to tackle people and quick and agile enough to react.

The DBs guard the WRs, and similarly, they are fast and agile, and because of their job requirements, are often the best athletes on the team. The DBs also tackle RBs, which would not be good, because that would indicate that the RB has gained a lot of yardage.