Hash marks are short lines, running perpendicular to sidelines or sideboards, used to mark locations, primarily in sports.
In ice hockey, the hash marks are two pairs of parallel lines on either side of the face-off circles in both ends of the rink. Players must remain on their team's side of the hash mark nearest their own goal during a face-off until the puck hits the ice.
In American football and Canadian football, the hash marks are two rows of lines near the middle of the field that are parallel to the side lines. These small lines (about 1 yard long) are used to mark each of the 5-yard lines, which go from sideline to sideline. All plays start with the ball on or between the hash marks. That is, if the ball is downed in between a hash mark and the nearest sideline, it must be reset on the hash mark for the next play. The width of a standard football field in the United States is 160 feet (53⅓ yards).
Prior to the adoption of hash marks (which were first utilized at the first NFL playoff game in 1932), all plays began where the ball was declared dead, including extra point attempts.