When it happens:
Aug. 5 to Aug. 12
How it became a sport:
Not to be confused with the chair-throwing and costume-wearing of professional wrestling, which became famous in 1950s, freestyle and Greco-Roman wrestling is recognized as one of the oldest sports in the world. It was even mentioned in Homer's "Iliad," and cave drawings in France depict men executing many of the same moves used in modern Olympic wrestling.
The sport was originally established as a way for soldiers and civilians to properly train in combat. Wrestling was a part of the culture in ancient Greece—it was even taught in schools.
In the Olympics, there are two different styles of the sport, Greco-Roman and freestyle. While the rules are identical in both, Greco-Roman wrestling prohibits attacking your opponent below the waist, while freestyle wrestling allows grapplers to use both their arms and legs to apply moves and holds.
What it takes:
Excellent cardiovascular conditioning, as well as strength and speed. Wrestlers need the stamina of a marathon runner and the strength of a weightlifter—they don't stop moving throughout their matches and constantly have someone either on their back or looking to throw them across the floor.
How you win:
Matches are broken up into three two-minute periods, with a thirty-second break in-between. Whoever wins two periods first is the winner.
During the match, wrestlers score technical points for various maneuvers such as takedowns, reversals and throws. Points are also awarded for exposing your opponents back, a vulnerable position that allows a hold to be administered. Depending on how long a wrestler is in a hold, the combatant applying the hold can score points as well. If an opponent has six more points than his opponent, the period is stopped for technical superiority.
Classification points are what matters though. These determine the competitor's rank in the pool or bracket they are competing in.
However, it is how the technical points are added up that lead to the classification scoring. Simply put, if a wrestler has more technical points than his opponent, they win the match.
Scores are broken down in several ways. If a match is decided by fall, the score is 4-0. If a match is won by technical superiority with the loser left scoreless, the contest ends 4-0 as well. If the match ends due to technical superiority but the losing wrestler scores a point, the contest would result in a 4-1 score. If there is a shutout, with the opponent scoring zero technical points, the score is 3-0. If a match is won simply on points, without technical superiority, the contest ends with a 3-1 score.
And unlike professional wrestling, biting, groin strikes and any lock that could hurt the spine or neck are forbidden.
Exposure: When a wrestler exposes his back to his opponent for several seconds.
Escape: When a wrestler is able to go from a defensive position to a neutral one.
Double Leg Takedown: A common hold mastered by most amateur wrestlers. It involves the wrestler wrapping his arms around his opponents legs and using leverage to drive the opponent to the ground. Most wrestlers that get involved in Mixed Martial Arts later in life use this move to get an advantage on their opponents, who usually aren't strong fighters on the ground.
NBC Olympics Wrestling Guide