Why refs wait to hold up flag for offside in soccer

The offside rule is confusing for those watching soccer (world football) for the first time.It can be even more confounding when the assistant referees, those with the flags, wait to actually put their flags up for a while.It happened early in the World Cup Final between Argentina and Spain, and it probably will happen again.Here's how it works.MORE: Here's how to win a free Chipotle burrito during World Cup finalWhy are offside calls so delayed?This began in the VAR era of video reviews, and it's to ensure the call is right.The assistant referees are directed to let the run of play complete before calling what they believe to have been offside.That's because, if it wasn't actually offside, the result of the play should stand.If the assistant held up the flag, only for it to be determined