The trial begins on Monday - and is one of the most important in Apple's history.
Apple boss Tim Cook will be giving evidence, the first time he's given testimony at a trial.
At stake is the future of the App Store and the amount it charges developers - a wildly lucrative money spinner for the company.
In August last year, Epic Games laid a trap for Apple.
Its hit game Fortnite implemented its own in-app payment - bypassing Apple's 30% charges.
Apple promptly kicked Epic Games off the App Store.
But Epic Games was waiting for just that.
