How many players are on the field per team in a football (soccer) match?

A side fields eleven: ten outfield players and one goalkeeper, the only player allowed to handle the ball, and then only inside his or her own penalty area. The number was fixed in the earliest codified rules of the game in the nineteenth century, borrowed from the eleven-a-side convention already common in English public school games and cricket, and it has stayed put ever since while almost everything else about the sport has changed. What matters more in practice is the lower limit. If sendings-off or injuries reduce a team below seven players on the pitch, the match is abandoned, which is why a side down to eight will often defend rather than risk another card. Substitutions do not change the count on the field, only who is filling the eleven slots, and the number of permitted substitutions varies by competition while the eleven does not.

The formation numbers coaches quote, such as 4-4-2, always add to ten because the goalkeeper is assumed.