For the sake of clarity and for anyone who is wondering what it means when people talk about the number 10 in soccer, let me quickly explain. The number 10 refers to either: the player on the soccer field who is wearing the number 10 on the back of their jersey in a specific game ; or it can refer to the position on the field that is associated with the number 10. Each player in a soccer game is required to wear a number on the back of their jersey to identify them clearly.
They wore No. 10 while starring on the biggest stages for their countries and were vital to giving the number its meaning and sense of mystique. Today, the best soccer players strive to earn the honor of wearing the number 10 jersey for their team, because it’s attached to such prestige and is a sign of earned respect.
The Number 10 is a master of the soccer fundamentals. The player’s passing, dribbling, and ball control are his specialty. Every time he receives the ball, he's able to reset or continue the play. Some of the best Number 10 players aren't breathtakingly fast, but, with their technical ability, can find space and relax the flow of the game.
Unlike any jersey number in any other sport, the No. 10 jersey in soccer carries with it a certain caché, a sense of prestige, a sign of respect.
The classical No.10 was a string-pulling midfielder, typically with technique dripping from every pore, playing in the hole behind his team’s central striker.
Traditionally Assigned Soccer Position Number: 10. Their role is similar to that of the center midfielders, but more focused on attacking (shooting, assisting, scoring).
Number 10 remains the play-maker, witness Messi. Number 9 remains the striker or key goalscorer. So if we look at the common 4-2-3-1 formation, this is how it plays out today: Numbers 6 and 8 are used to describe holding midfielder positions, regardless what number is on the back of a player’s shirt.
Answer (1 of 4): There is some very useful info expressed in this thread about formations and numbering: What number does a ball winning midfielder commonly wear?