What does offside mean?
Picture this. You are an attacker on the football pitch, standing close to the other team's goal. Your teammate has the ball, and they are about to pass it to you. There is one big rule you must follow: you cannot be closer to the goal than the last defender on the other team. If you are, the referee blows the whistle, and the goal will not count.
Picture a line drawn right across the field, at the last defender's feet. You have to stay behind that line until your teammate actually passes the ball. Step over it too early, and you are offside.
A player is offside if, right when a teammate passes them the ball, they are closer to the goal than the last defender on the other team.
A robot referee
This call happens fast, and it really matters, so real referees get some help. At the 2026 World Cup, FIFA uses a smart AI camera system in every stadium to help make the offside call.
The system uses 12 cameras. They track 29 points on every player's body, 50 times every single second. That is enough information to draw the invisible offside line and make the call in just a couple of seconds. Today, you get to be that AI referee.
AI stands for Artificial Intelligence. It means a computer that has learned to do a smart job, like spotting patterns or making a call, almost like a person would.
Below is a play from a real match. Three players are on the screen. Your job: decide if the attacker is onside or offside, then check your answer with the AI.
Play the Game AI Ref Challenge 🤖
Watch the three dots on the field. Teal is your teammate, passing the ball. Orange is the attacker, who might be offside. Navy is the last defender. The AI helper in this game is called VAR (that's short for Video Assistant Referee).
How to play
- Look carefully at who is closer to the goal. The goal net is on the right.
- Tap ONSIDE or OFFSIDE, your best guess.
- Press "Check with VAR" to see the AI's line and the real answer.
- Play all 5 rounds and see how many you get right.
This is not made up for the game. At real World Cup stadiums, 12 cameras track 29 points on every player's body, 50 times every second. That is how the AI draws the offside line and helps the referee make the call, for real, in just a couple of seconds.
- A player is offside if they are closer to the goal than the last defender when the ball is passed to them.
- Picture a line at the last defender's feet: attackers must stay behind it until the pass is made.
- AI is a computer that has learned to do a smart job, like spotting patterns or making a call.
- At the World Cup, an AI camera system tracks every player 50 times a second to help referees make the offside call.
🎮 3D Vox game: You are the VAR
Each play rides the conveyor. You make the call: onside or offside? The computer checks you, just like VAR!
Next: help the coach pick the right formation by asking smart questions.