Original: For the pay-per-view, see WWF InVasion. The Invasion was a professional wrestling storyline in the World Wrestling Federation (WWF) (known now as World Wrestling Entertainment or WWE) that began shortly after the WWF's purchase of World Championship Wrestling (WCW).
Simplified: The Invasion was a wrestling storyline in the World Wrestling Federation (WWF) that began after the WWF bought World Championship Wrestling (WCW).