Squad numbers are used in association football to identify and distinguish players who are on the field. Numbers very soon became a way to also indicate position, with starting players being assigned numbers 1–11. However, there is no fixed rule; numbers may be assigned to indicate position, alphabetically by name, according to a player's whim, randomly, or in any other way. In the modern game they are often influenced by the players' favourite numbers and other less technical reasons, as well as using "surrogates" for a number that is already in use. However, numbers 1–11 are often still worn by players of the previously associated position.

As national leagues adopted squad numbers and game tactics evolved over the decades, numbering systems evolved separately in each football scene, and so different countries have different conventions. Still, there are some numbers that are universally agreed upon being used for a particular position, because they are quintessentially associated with that role.

For instance, "1" is frequently used by the starting goalkeeper, as the goalkeeper is the first player in a line-up. "9" is usually worn by strikers, also known as centre-forwards, who hold the most advanced offensive position on the pitch, and are often the highest scorers in the team. "10" is one of the most emblematic squad numbers in football, due to the sheer number of football legends that have worn the number 10 shirt; forwards, playmakers, second strikers, and attacking midfielders have worn this number.

History First use of numbers The first record of numbered jerseys in football date back to 1911, with Australian teams Sydney Leichhardt and HMS Powerful being the first to use squad numbers on their backs.The Secret Lives of Numbers: The Curious Truth Behind Everyday Digits by Michael Millar, Virgin Books, 2012 – One year later, numbering in football would be ruled as mandatory in New South Wales.Así nació la tradición de usar números en las camisetas by Gustavo Farías on La Voz del Interior, 22 August 2013

The next recorded use was on 23 March 1914 when the English Wanderers, a team of amateur players from Football League clubs, played Corinthians at Stamford Bridge, London. This was Corinthians' first match after their FA ban for joining the Amateur Football Association was rescinded. Wanderers won 4–2.

In South America, Argentina was the first country with numbered shirts. It was during the Scottish team Third Lanark tour to South America of 1923, they played a friendly match v a local combined team ("Zona Norte") on 10 June. Both squads were numbered from 1–11.El número 10, la camiseta que se convirtió en un emblema by Leonardo Peluso on Página/12, 3 February 2018

In the United States, the first football match with squad numbers was played on 30 March 1924 when the Fall River F.C. played St. Louis Vesper Buick during the 1923–24 National Challenge Cup. Only the local team wore numbered shirts.Historia y curiosidades de la numeración fija en el fútbol by Walter Raiño on Clarín, 13 September 2017

The next recorded use in association football in Europe was on 25 August 1928 when The Wednesday played Arsenal"Gunners wear numbered shirts", Arsenal.com, 6 July 2007 and Chelsea hosted Swansea Town at Stamford Bridge. Numbers were assigned by field location:

Goalkeeper Right full back (right side centre back) Left full back (left side centre back) Right half back (right side defensive midfield) Centre half back (centre defensive midfield) Left half back (left side defensive midfield) Outside right (right winger) Inside right (attacking midfield) Centre forward Inside left (attacking midfield) Outside left (left winger)

In the first game at Stamford Bridge, only the outfield players wore numbers (2–11). The Daily Express (p. 13, 27 August 1928) reported, "The 35,000 spectators were able to give credit for each bit of good work to the correct individual, because the team were numbered, and the large figures in black on white squares enabled each man to be identified without trouble." The Daily Mirror ("Numbered Jerseys A Success", p. 29, 27 August 1928) also covered the match: "I fancy the scheme has come to stay. All that was required was a lead and London has supplied it." When Chelsea toured Argentina, Uruguay and Brazil at the end of the season in the summer of 1929, they also wore numbered shirts, earning the nickname "Los Numerados" ("the numbered") from locals.

A similar numbering criterion was used in the 1933 FA Cup Final between Everton and Manchester City. Nevertheless, it was not until the 1939–40 season when The Football League ruled that squads had to wear numbers for each player.The 'most novel cup final in the history of football' By Gareth Thomas on The Football History Boys - April 14, 2020

Early evolutions of formations involved moving specific positions; for example, moving the centre half back to become a defender rather than a half back. Their numbers went with them, hence central defenders wearing number 5, and remnants of the system remain. For example, in friendly and championship qualifying matches England, when playing the 4–4–2 formation, generally number their players (using the standard right to left system of listing football teams) four defenders – 2, 5, 6, 3; four midfielders – 7, 4, 8, 11; two forwards – 10, 9. This system of numbering can also be adapted to a midfield diamond with the holding midfielder wearing 4 and the attacking central midfielder wearing 8. Similarly, the Swedish national team number their players: four defenders – 2, 3, 4, 5; four midfielders – 7, 6, 8, 9; two forwards – 10, 11.

The 1950 FIFA World Cup was the first FIFA competition to see squad numbers for each players,De 'Nuestro Hirosima' al surgimiento de los números como dorsales by Javier Estepa on Marca but persistent numbers would not be issued until the 1954 World Cup, where each man in a country's 22-man squad wore a specific number from 1 to 22 for the duration of the tournament.

Evolution

In 1993, The Football Association (The FA) switched to persistent squad numbers, abandoning the mandatory use of 1–11 for the starting line-up. The first league event to feature this was the 1993 Football League Cup Final between Arsenal and Sheffield Wednesday, and it became standard in the FA Premier League the following season, along with names printed above the numbers. Charlton Athletic were among the ten Football League clubs who chose to adopt squad numbers for the 1993–94 season (with squad numbers assigned to players in alphabetical order according to their surname), before reverting to 1–11 shirt numbering a year later.

Squad numbers became optional in the three divisions of the Football League at the same time, but only 10 out of 70 clubs used them. One of those clubs, Brighton & Hove Albion, issued 25 players with squad numbers but reverted to traditional 1–11 numbering halfway through the season. In the Premier League, Arsenal temporarily reverted to the old system halfway through that same season, but reverted to the new numbering system for the following campaign. Most European top leagues adopted the system during the 1990s. The Football League made squad numbers compulsory for the 1999–2000 season, and the Football Conference followed suit for the 2002–03 season.

The traditional 1–11 numbers have been worn on occasions by English clubs since their respective leagues introduced squad numbers. Premier League clubs often used the traditional squad numbering system when competing in domestic or European cups, often when their opponents still made use of the traditional squad numbering system. This included Manchester United's Premier League clash with Manchester City at Old Trafford on 10 February 2008, when 1950s style kits were worn as part of the Munich air disaster's 50th anniversary commemorations.

Players may now wear any number, as long as it is unique within their squad, between 1 and 99.

In continental Western Europe this can generally be seen:

Goalkeeper Right Back Left Back Centre Back Centre Back (or Sweeper, if used) Central Defensive/Holding Midfielder Right Attacking Midfielder/Winger Central/Box-to-Box Midfielder Striker Attacking Midfielder/Playmaker Left Attacking Midfielder/Winger

This changes from formation to formation, although the defensive number placement generally remains the same. The use of inverted wingers now sees traditional right wingers (the number 7s, like Cristiano Ronaldo) on the left and traditional left wingers (the number 11s, like Gareth Bale) on the right.

Numbering by country

Argentina

Argentina developed its numeration system independently from the rest of the world. This was because until the 1960s, Argentine football developed more or less isolated from the evolution brought by English, Italian and Hungarian coaches, owing to technological limitations at the time in communications and travelling with Europe, lack of information as to keeping up with news, lack of awareness and/or interest in the latest innovations, and strong nationalism promoted by the Asociación del Fútbol Argentino (for example, back then Argentines playing in Europe were banned from playing in the Argentine national team).

The first formation used in Argentine football was the 2–3–5 and, until the 1960s, it was the sole formation employed by Argentine clubs and the Argentina national football team, with only very few exceptions like River Plate's La Máquina from the 1940s that used 3–2–2–3. It was not until the mid 1960s in the national team, with Argentina winning the Taça das Nações (1964) using 3–2–5, and the late 1960s, for clubs, with Estudiantes winning the treble of the Copa Libertadores (1968, 1969, 1970) using 4–4–2, that Argentine football adopted European formations on major scale, and mirrored its counterparts on the other side of the Atlantic.

While the original 2–3–5 formation used the same numbering system dictated by the English clubs in 1928, subsequent changes were developed independently.

The basic formation to understand the Argentine numbering system is the 4–3–3 formation, used by the coach César Menotti for the team that won the 1978 World Cup. The squad numbers are:

1 Goalkeeper 4 Right Back 2 First Centre Back / Sweeper 6 Second Centre Back / Stopper 3 Left Back 8 Right Midfielder 5 Central Defensive Midfielder 10 Left Midfielder 7 Right Winger 11 Left Winger 9 Striker

Brazil

In Brazil, the 4–2–4 formation was developed independently from Europe, thus leading to a different numbering – here shown in the 4–3–3 formation to stress that in Brazil, number ten is midfield:

1 Goleiro (Goalkeeper) 2 Lateral Direito (right wingback) 3 Zagueiro Direito (right centre back) or Beque Central (centre back) "STOPPER" 4 Zagueiro Esquerdo (left centre back) or Quarto Zagueiro (the "Quarterback", almost the same as a centre back) "SWEEPER" 6 Lateral Esquerdo (left wingback) 5 Primeiro Volante ("Rudder" or "mobile", the defensive midfielder) 8 Segundo Volante (central midfielder) or Meia Armador (playmaker) 10 Meia Atacante (attacking midfielder) or Meia Esquerda (left midfielder, generally more offensive than the right one) 7 Ponta Direita (right winger) or Meia Direita (right midfielder) 9 Centroavante (centre-forward/striker) 11 Ponta Esquerda (left winger) or Segundo Atacante (secondary striker)

When in 4–2–4, number 10 passes to the Ponta de Lança (striker), and 4–4–2 formations get this configuration: four defenders – 2 (right wingback), 4, 3, 6 (left wingback); four midfielders – 5 (defensive), 8 ("second midfielder"), similar to a central midfielder), 7, 10 (attacking); two strikers – 9, 11

In Brazilian football, the number 24 is historically shunned because of "jogo do bicho," an illegal underground lottery. In this game, the number 24 represents the deer ("veado" in Portuguese), which sounds nearly identical to a common homophobic slur in Brazil.

France