The offside rule explained simply — with clear examples

No rule in football starts more arguments than offside. The good news: the core idea is simple once you strip away the noise. Here it is in plain English.

The one-sentence version

A player is offside if they are nearer to the opponent's goal line than both the ball and the second-to-last defender at the moment a teammate plays the ball to them — and then get involved in the play.

The "second-to-last defender" is usually the last outfield defender, because the goalkeeper is normally the last. So in practice you compare the attacker to the last defender.

The three things that must all be true

For an offside offence, every one of these has to apply:

1. The attacker is in the opponent's half.

2. They are ahead of the ball and the last defender when it's played.

3. They become involved in active play — touching the ball, challenging an opponent, or gaining an advantage from that position.

Miss any one of those and there is no offence.

When you are NOT offside

• You can never be offside in your own half.
• You are not offside if you're level with the last defender (or the ball).
• There is no offside straight from a goal kick, throw-in or corner.
• Being in an offside position is not an offence on its own — only if you get involved.

Position vs. offence

This is the part fans miss. A striker can stand in an offside position all day and it means nothing. The flag only goes up when the ball is played and that player interferes — receiving it, blocking the keeper, or playing a rebound. That's why you sometimes see a player in front of the defence and no flag: they didn't touch the ball or affect anyone.

How technology calls it now

At the top level, semi-automated offside technology uses multiple cameras and a sensor in the ball to track players' limbs many times a second. It flags the exact frame the ball is played and measures whether any legal part of the attacker's body is beyond the last defender — then sends an animated 3D replay to the screens. It turns a split-second judgment into a measured one, which is why marginal calls now take a moment but come with a picture.

Want to see offside calls in context? Follow the action live in our match centre.