---
slug: "los-line-of-scrimmage"
title: L.O.S.
depth_tier: entry
side: UNIVERSAL
category: Rules
source_id: "FLD-0018"
created: 2026-04-06
updated: 2026-05-18
canonical: https://learningfootball.xyz/terms/los-line-of-scrimmage
---
# L.O.S.

## Short Definition

The imaginary line at the forward point of the ball before each snap—establishing where players must align and defining the neutral zone between teams.

## Definition

The line of scrimmage is the starting point of every play—the imaginary line drawn across the full width of the field at the forward point of the ball before the snap. It defines the legal pre-snap boundaries for both teams: offensive players must be behind it (or on it for linemen), and defensive players must be behind their side of it. When either team violates this boundary before the snap, it creates a neutral zone infraction.

The LOS resets after every play at the new spot of the ball, which is determined by the official's spot at the end of the previous play's forward progress. Every measurement in football originates from the line of scrimmage—gains and losses are measured from it, yardage penalties are assessed from it, and the first-down chain is set ten yards beyond it. The phrase "from the previous spot" in penalty enforcement language always refers to the previous line of scrimmage.

In coaching and analysis, the LOS is the universal positional reference. "Getting off the ball at the LOS" describes a lineman's snap reaction. "Winning at the line of scrimmage" describes a team that physically dominates the point of attack. "Getting into the backfield" means a defender crossed the LOS before the ball carrier. The entire language of football position is organized around this single reference line.

The neutral zone—the space occupied by the football itself, extending the width of the ball around it—surrounds the LOS and is the territory no player from either team can enter before the snap. The LOS runs along each team's side of the neutral zone: the offensive line of scrimmage is the front edge of the ball; the defensive line of scrimmage is the back edge. Defenders who enter the neutral zone before the snap risk encroachment or offside calls depending on whether they contact an offensive player.

## Example

"Defensive end crosses the LOS before the snap and makes contact with the offensive tackle. Encroachment—the LOS is the boundary both teams must respect until the center releases the ball. Everything in pre-snap alignment is measured against where that line is."

## Common Confusion

The line of scrimmage and the neutral zone are related but distinct. The neutral zone is the space the ball occupies—between the tips of the ball—and extends the width of the ball around it. Defenders cannot enter the neutral zone before the snap. The LOS is the line on each team's side of the neutral zone.

## Related

- C.P.
- GAP SOUND
- KILL
- MIKE/RE-MIKE
- general-football-term

---
Source: https://learningfootball.xyz/terms/los-line-of-scrimmage