number of substitutions allowed in world cup football
Substitute (association football) Most competitions only allow each team to make a maximum of three substitutions during a game and a fourth substitute during extra time, although more substitutions are often permitted in non-competitive fixtures such as friendlies. A fourth substitution in extra time was first implemented in recent tournaments, including the 2016 Summer Olympic Games, the 2017 FIFA Confederations Cup and the 2017 CONCACAF Gold Cup final.[1][2][3][4][5] A fourth substitute in extra time has been approved for use in the elimination rounds at the 2018 FIFA World Cup, the UEFA Champions League and the UEFA Europa League.[6][7] Each team nominates a number of players (typically between five and seven, depending on the competition) who may be used as substitutes; these players typically sit in the technical area with the coaches, and are said to be "on the bench". When the substitute enters the field of play it is said they have come on or have been brought on, while the player they are substituting is coming off or being brought off.
Squad number (association football) Squad numbers are used in association football to identify and distinguish players that are on the field. Numbers were originally used to also indicate position, with starting players being assigned numbers 1–11, although these numbers often bear little or no significance in the modern game other than the players' favourite numbers and the numbers available. However, numbers 1–11 are often still worn by players of the previously associated position.[1]