Not the big-money US-style wrestling that has made The Rock and The Undertaker so famous, but something much more traditional.
There are two disciplines within it, greco-roman and freestyle.
In greco-roman, holds are only allowed above the waist, but in freestyle, wrestlers can grab any body part they like.
Matches are split into two three-minute halves, and the aim is to pin your opponent's back to the mat for two seconds, which is enough for victory.
If at the end of the match neither wrestler has managed to pin the other then it is decided on points, unless one wrestler earns a 10-point lead, in which case they are the winner.
Women's wrestling is included in the Games for the first time in Athens.
It was one of the first sports, dating back to the very first Olympics thousands of years ago, although the sport hasn't been in every Games since.