NFL 101
New to football, or just to the stats side of it? Start here. Seven quick sections: scoring, the field, penalties, each unit, and a glossary that decodes every stat this site actually uses.
"Every game comes down to one thing: who put more points on the board. Here's every way to score."
Touchdown (6 points)
The offense gets the ball into the opponent's end zone, by running it in or catching it there. Worth 6 points, the biggest single score in the game.
Extra Point (PAT, 1 point)
After a touchdown, the team gets one free kick from close range for 1 more point. Almost always good. It's the two-point try (below) that's the real decision.
Two-Point Conversion (2 points)
Instead of kicking the extra point, the offense can run one more play from close range. Succeed and it's worth 2 points instead of 1. Riskier, but sometimes the math (or the score) demands it.
Field Goal (3 points)
When the offense stalls but is close enough, the kicker can try to boot the ball through the uprights for 3 points instead of risking a turnover.
Safety (2 points)
If the offense gets tackled (or steps out of bounds) inside its own end zone, the DEFENSE scores 2 points and gets the ball back. Rare, and a real momentum-killer.
"An offense gets 4 tries to move 10 yards. Miss all 4, and the other team takes over. That's the whole game, really."
Down
One play. The offense gets 4 of them (a "set of downs") to gain 10 yards. Gain 10 and the count resets to 1st down; fail all 4 and the ball goes to the other team where it sat.
"4th & 1" notation
How every situation on this site is written: down & yards-to-go. "4th & 1" means it's the 4th and final try, needing just 1 more yard. "1st & 10" is a fresh set of downs.
Red Zone
Inside the opponent's 20-yard line, close enough to score that the whole game tightens up. Field zone in Play Search filters on exactly this.
Turnover on Downs
Failing to convert on 4th down. The ball simply goes to the other team where it sat, no kick involved. This exact decision is what the site's own Fourth-Down Analyzer prices in expected points.
First Down
Gaining the 10 yards needed resets the down count back to 1st down: the offense keeps the ball and gets 4 fresh tries.
"Not every rule gets broken on purpose. These are the ones that show up the most. Play Search's own penalty filter catches all of them directly."
False Start (5 yards)
An offensive player moves before the snap. Automatic 5-yard penalty and the down replays. The single most common penalty in football.
Offside (5 yards)
A defensive player crosses the line of scrimmage before the snap. Same idea as a false start, just committed by the other side.
Holding (10 yards)
Grabbing or hooking an opponent instead of blocking or tackling cleanly. Called on offense or defense, and it's the penalty announcers argue about most, since it happens on almost every play but only sometimes gets flagged.
Pass Interference (PI)
Illegally contacting a receiver before the ball arrives. Not a fixed yardage: the ball is placed at the spot of the foul, which can be a huge swing on a deep pass.
Roughing the Passer (15 yards)
Hitting the quarterback late, low, or with excessive force after he's thrown the ball. 15 yards and an automatic first down: one of the most game-changing penalties there is.
Personal Foul / Unsportsmanlike Conduct (15 yards)
Anything from a late hit to trash talk to taunting. 15 yards, and if it's bad enough, the player can be ejected.
"The offense has the ball and is trying to score. Here's who does what."
Quarterback (QB)
Takes the snap and runs the offense: throwing, handing off, or running it himself. The single most valuable position in football, which is why QB form gets its own feature in this site's model.
Running Back (RB)
Takes handoffs and runs the ball upfield. Also catches passes out of the backfield.
Wide Receiver (WR) / Tight End (TE)
WRs line up wide and catch passes downfield. TEs do the same but line up next to the offensive line and also block: a hybrid blocker/receiver.
Offensive Line (OL)
The five players up front who block for the quarterback and running backs. They rarely touch the ball and rarely make highlight reels, but nothing works without them.
Run vs. Pass
The two basic play types. A run hands the ball to someone who tries to gain yards on the ground; a pass throws it downfield. Play Search lets you filter either one directly.
Shotgun vs. Under Center
Under center, the QB stands right behind the line and takes the snap directly. In shotgun, he stands a few yards back, giving more time to read the defense before a pass.
"The defense is trying to stop them, or take the ball away outright."
Defensive Line (DL)
The front wall trying to stop the run and pressure the quarterback, lined up directly across from the offensive line.
Linebacker (LB)
Line up a few yards behind the defensive line. Do a bit of everything: stop the run, cover receivers, blitz the passer.
Defensive Back (DB) / Secondary
Cornerbacks and safeties, lined up deepest. Their job is covering receivers and defending the pass. An interception is the best possible day at the office.
Sack
The defense tackles the quarterback behind the line of scrimmage before he can throw. A genuine outcome you can filter for directly in Play Search.
Interception (INT)
A defender catches a pass meant for the offense: instant turnover, ball goes the other way. One of the biggest single swings in a game.
Blitz
The defense sends extra players to rush the quarterback instead of covering receivers. High risk, high reward: more pressure, but fewer defenders left in coverage.
"The kicking game. Easy to ignore, but it constantly swings field position, and sometimes whole games."
Kickoff
How each half starts, and after every score too: one team kicks the ball deep to the other, who tries to return it as far as possible.
Punt
When the offense stalls and isn't close enough for a field goal, it kicks the ball away instead of risking a turnover on downs. It trades field position for possession.
Field Goal Attempt
The kicker tries to boot the ball through the uprights from wherever the offense stalled out. 3 points if it's good.
Kick / Punt Return
The receiving team's chance to gain free field position by running the ball back after a kickoff or punt.
Onside Kick
A short, deliberately bounce-y kickoff. The kicking team is gambling it can recover its own ball instead of giving the other team a normal return. Almost always a late-game, trailing-team move.
"This is the one I'd actually bookmark. Every stat word this site uses, in plain English."
EPA (Expected Points Added)
The core stat behind almost everything on this site. Every game situation has an expected point value; EPA is how much a single play moved that value. A 3-yard gain on 3rd & 2 helps a lot (positive EPA); the same 3 yards on 3rd & 10 barely matters.
Win Probability
This site's core prediction: the model's estimate of how likely a team is to win, before kickoff. "65%" means: in games it rated this way, that team has actually won about 65% of the time, checked against the track record, not just claimed.
Success Rate
The share of plays with positive EPA, a "successful" play by that measure. Shown alongside EPA/play in Play Search results because a team can have a great average EPA on the back of a few huge plays while succeeding less often than it looks.
4th-Down "Go" Math
Going for it, kicking a field goal, and punting all have a real expected-points value, computed the same way for every team and situation. The Fourth-Down Analyzer prices all three and flags when the actual call cost real points.
Garbage Time
Late in a blowout, once the outcome is basically decided, teams play differently (a leading defense sits back, a trailing offense throws every down), which can quietly distort a team's raw stats if it isn't excluded.
Explosive Play
A big chunk gain in one shot. This site's definition (also a Play Search filter) is 15+ yards through the air or 10+ on the ground.
"Rolling" Form (last 8 games)
This model rates a team on its last 8 games, not its full-season average. Recent form matters more than what happened in Week 1. It's why a team's power ranking can move even in weeks it doesn't play a marquee opponent.