This is a list of WWE pay-per-view events, detailing all professional wrestling cards promoted as pay-per-view (PPV) by WWE on the WWE Network or selected broadcasters worldwide. WWE has broadcast pay-per-views since the 1980s, when its classic "Big Four" events (Royal Rumble, WrestleMania, SummerSlam, and Survivor Series) were first established. The company's PPV lineup expanded to a monthly basis in the mid-1990s and reached its peak of sixteen shows a year in 2006 before returning to twelve in 2012. Following the second brand extension in July 2016, the number of shows per year were expanded once again to 16. Pay-per-view shows are typically three hours in length, though budget priced events (e.g., In Your House) were shorter, while premium events such as WrestleMania can approach five hours. Since 2008, all WWE pay-per-views have been broadcast in high definition. Pay-per-view events are a significant part of the revenue stream for WWE.