Although everybody is now used to soccer players wearing their name and squad number on the back of their jerseys[female soccer jersey], this was not always the case. In the early days of the game, it was normal practice for players to take to the field with nothing emblazoned on the back of their shirts.

Adding numbers – player names would come much later with the advent of squad numbers – was an innovation intended to help spectators understand the exact position on a field of a particular player. 

There is some dispute about when the practice was first introduced. There are examples of it being used in Australian soccer as early as 1911, and in a pre-war amateur match in England between the English Wanderers and the Corinthians.

Argentina is believed to be the first country to adopt the practice locally, but the first recorded use in an accredited league was in August 1928, when Sheffield Wednesday played Arsenal.

Numbers were strictly allocated according to the location of a player on the field. Number one was the goalkeeper, two and three reserved for the two full-backs and four and five used by the centre-half pairing. Number nine was always the centre-forward, whilst seven and eleven were associated with the right and the left-wing, respectively.

Until the mid-1960s this simple system sufficed because there were no substitutes allowed. Even when they were introduced, they would be allocated higher numbers – 12, 14, 15, for example. Many clubs and players refused to allow a player to take the field wearing the number 13 shirt, though, because it is associated with bad luck. 

Numbering jerseys in sequential number order was practical. It meant that if a player was injured or out of form, a player could be slotted into a team in his position, either wearing the same shirt or at least with the same number.

And, in the days before commercialisation of the game, there was no money to be made selling replica shirts with any particular number on it. Indeed, parents would often sew children’s favourite numbers on the back of jerseys themselves.

Squad numbers – 1 to 23 – were first used in the 1950 World Cup, although Argentina chose an unusual method of assigning numbers to players for the World Cups between 1974 and 1982, with numbers allocated according to surname order, with the exception of Diego Maradona who was given the number 10 shirt.

And, when Brazil forgot to give their players squad numbers for the 1958 World Cup, a FIFA official randomly did it for them, handing the number 10 shirt to a 17-year old called Pelé.

In 1993 the FA decided to abandon the traditional system in favour of squad numbers, with Arsenal and Sheffield Wednesday again the pioneers in the League Cup Final of that year. By 1999 it was compulsory through the Football League in England, and leagues around the world followed suit.

Now players may wear any number on the back of their jersey, provided it falls within the range 1 – 99. 

However, some players have worn numbers higher than that for commemorative purposes. For example, Mexican player Jesus Arellano took to the field with the number 400 on is back in 1998 to celebrate the 400^th anniversary of the city of Monterrey. A number of players – Martin Jørgensen of Denmark, Andreas Herzog of Austria, and Aaron Mokoena of South Africa – have donned 100 to celebrate a century of international caps for their country. And when Jamaican sprinter Usain Bolt took part in a charity match at Old Trafford in 2018, his shirt number was 9.58, in honour of his 100 meters world record time.

Certain shirt numbers are more popular than others, with number seven, nine and ten amongst the most enduring, because they have been worn by some of the most skilful players of the game in the past. They often generate the most in merchandising revenue as a result also.

At a club like Manchester United, for example, some of the greatest players in the club’s recent history have worn the number seven shirt – George Best, Bryan Robson, Eric Cantona, David Beckham, and Cristiano Ronaldo.  Seven is also popular because in a number of cultures it is traditionally associated with luck – soccer players are notoriously superstitious.

Meanwhile number nine is always associated with strikers, like Alan Shearer, Samuel Eto’o and, from the current generation of players, the likes of Robert Lewandowski and Karim Benzema. As for the number ten that has been graced by some of the greatest players ever to play the game – Maradona, Pelé, Lionel Messi, Zinedine Zidane, and Dennis Bergkamp to name but a few.

Another jersey number that has become synonymous with skilful players is number 14. This was first popularised by Johann Cruyff when he was at Ajax, and he insisted on wearing it when he went to Barcelona and whilst playing for the Dutch national team. Later, Thierry Henry chose the number when he went to Arsenal and broke the club’s goalscoring record, and his successor, Pierre-Emerick Aubameyang, has also opted to wear it.

A recent fashion for star players is to wear the number 23. This is in homage to basketball legend Michael Jordan and is the number that he wore for the Chicago Bulls in his playing days. David Beckham, Thiago Motta, and Wesley Sneijder are just some of the many men who have chosen this number.

Finally, there are certain numbers which have been retired by certain clubs in honour of players who have had long and glorious histories with the team. This practice, which has been borrowed from North American sports, only became possible when sequential numbering was abandoned in favour of squad numbers. 

Some of the best-known examples are West Ham and the number six shirt, associated with Bobby Moore, who captained England to World-Cup success in 1966; number three as AC Milan retired it to honor club legend Paolo Maldini; and the number 10 shirt at Napoli, forever associated with Diego Maradona’s time at the club.