It's the single most controversial rule in all of soccer. To this day, 163 years since the rule was invented and codified, no fan truly understands how offside works. Despite its complicated nature, the offside rule is arguably the most important to enforce.

The law governing its modern application has 45 clauses and runs to more than 1,000 words. A former Premier League referee explains all

For a few moments, it looked like Iran had found the goal that would send it through. Then VAR stepped in.

The biggest single culprit in Iran’s failure to advance to the knockout phase is a weird idiosyncracy to the offside law that has long outlived its usefulness.

There was a hugely dramatic finish to Egypt and Iran's 1-1 draw in Seattle, including an unusual - and tight - VAR offside call

Julian Quinones was beyond the last Ecuador defender. Despite that, the Mexican winger wasn't called offside. Half a field later, Quinones had tucked away the match's first goal for a 1-0 Mexico lead at home in Mexico City.

Cristiano Ronaldo has an equalising goal ruled out for offside during Portugal's round of 32 game with Croatia in Toronto.