A replay is when a video is played for a second time. This technique is used very frequently in sports, but also serves a role in surveillance. In surveillance, replay is used to gather data related to an event that was recorded, allowing for evidence to be collected and used for legal purposes. In sports, a replay is used to enhance the broadcast.
Sports broadcasts often use a replay to show an exciting or significant sports play for a second time. Replays are often slowed down or even frozen so that important parts of the play are easy for the audience to see. Graphics are sometimes drawn over the footage, such as circles and arrows, to highlight incidents that fans might otherwise miss, such as an unexpected injury. When something is replayed not long after it has occurred, this is called an instant replay.
The replays are typically shown during a lull in the action to keep the audience engaged. For example, when referees are discussing a play, an instant replay might be shown from earlier in the game to keep the broadcast from becoming boring.
Replays also take advantage of multiple camera angles. Since only one camera angle can be shown at once, an instant replay allows the same event to be shown from multiple angles.
This is commonly used in races, where crashes can be so complex that they are difficult to make sense of without watching them from multiple angles. A replay also serves a more practical function. They are often shown after a play to allow referees to make a call. Certain events can happen so quickly that it is difficult to identify what has occurred. As a result, the referees will have to watch recorded footage a second time to make a more accurate call. Popular replays are also used after a player has violated a rule in a game to allow officials to determine whether they should penalize the player.