On 15 April 1989, at an FA Cup semi-final, Liverpool supporters gathered on the terraces of Sheffield Wednesday's ground, Hillsborough Stadium.
The crowding turned into a crush and 96 people died, with hundreds more being injured.
Families of the people who died have campaigned for many years to find out what happened on the day of the disaster.
Now the results of a special investigation, called an inquest, have been announced.
It says that the police, ambulance service and other organisations made mistakes that led to the disaster. It also says that the fans were not to blame.
Ayshah's been looking at what happened on that day.