Olympic rosters are generally hand-picked by the national coaching squad of the sport or determined by measured performances at Olympic trials. In sports like track and field and swimming, athletes qualify for a trial by obtaining a designated time in a sanctioned event.
Some team sports may also have official tryouts, with invitees selected based on reputation, rankings and previous success. The National Olympic Committee of each country is responsible for supporting each athlete and entering him into the Games. All athletes must additionally comply with the Olympic Charter and follow the rules set forth by the International Federation that governs their respective sport.