The kids who walk out with the players are called "player escorts" or "mascot children," and they've been part of soccer games for well over 20 years.
You have seen it before every World Cup game, and pretty much every professional soccer game played everywhere in the last few decades. A star-struck kid follows a player onto the field before standing in front of him while the crowd sings the national anthems.
Kids who walk out with the players are known as "player escorts" or "mascot children," and they have been a part of football matches for over 20 years. After a match between Liverpool and Everton in November 1996, one of the first images of children strolling as mascots was featured in the Liverpool Echo. Beginning about the year 2000, the practice of having one escort for each player, rather than simply one or two each squad, began.
Early on, having kids accompany the players doubled as a means to generate awareness for charitable organizations. Before the 2002 FIFA World Cup, FIFA and UNICEF collaborated on an initiative called 'Say Yes For Children' "to promote and protect the right of all children to healthy recreation and quality primary education," according to a UNICEF press release at the time.
"Children are being given a prime role at each match, accompanying each player on to the pitch in a symbolic action reminding football enthusiasts that they have a major role to play in building a world fit for children," the statement read.
Children would lead the players onto the field wearing FIFA/UNICEF "Say Yes" t-shirts" before each World Cup 2002 match.
How those kids are chosen?
Traditionally, teams make arrangements with local schools or junior teams to select mascots for each.
It is entirely up to these schools and teams to determine how a kid is chosen. The majority of the time, it is based on athletic skill. The best players are usually chosen first. This is not always the case, but you may expect it to be the case.
On a global scale, you are likely to come across a chief sponsor of a tournament or organization that is actively looking for mascots. The best example of this type of organization is McDonald's Player Escort Program. The company chooses children to participate in various FIFA competitions.
The local team will use several strategies to allow children to join. Different requirements will be addressed for each event, notably for exhibition, cup, or league games.
The most common example is how Arsenal allowed members of their Junior Gunners program to fill out a form and vote to be a player's mascot at the Emirates Cup.
The initial few occasions were due to a campaign, but children have continued to accompany or, in some cases, lead players out onto the field for nearly two decades now.
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