First, it's important to note that you may hear the following terms used interchangeably:
However, they may be broken down to refer to specific chunks of time. Let's go through each one individually.
Stoppage time or added time is the additional time that is tacked on to the end of each half and an additional period of extra time. Each half and extra period (extra time) can have stoppage time added to it.
This time is compiled by the head official, who keeps track of the time spent from things like:
In larger matches, the head official will communicate this amount of time to an official on the sideline, who will display it for players, coaches and fans to see.
You can see stoppage time on your TV indicated by a +2 or +4 (based on the # of minutes added).
Injury Time is often used interchangeably with Added Time, Stoppage Time, or Extra Time.
It is sometimes used in reference to the specific amount of time added to the end of soccer halves as a result of injury-related occurrences.
After a half or extra period ends, it is possible for stoppage time will take place. Stoppage time typically lasts between one and nine minutes of additional time. Stoppage time is announced by the fourth official located on the sideline.
During stoppage time, the tempo of play may change depending on the score. If play is tied and the game is still in regulation, both teams will play more conservatively, preserving their energy for overtime. If one team is losing and the match is a high stakes situation, such as an elimination game, the team that is behind will push aggressively for goal scoring chances.
You may also see coaches making more substitutions during stoppage time, especially in overtime. This is because players who are rested can sometimes make an immediate impact on the game. The slang term "super sub" refers to a player who comes on late in the game and scores a game-winning goal. Another reason coaches make substitutions during stoppage time is, if they anticipate the match ending in a penalty shootout, coaches want their best penalty kick takers on the field.