World Record - Tallest meets smallestA world record is the best performance in a certain discipline, usually a sports event. In the United States the form world's record was formerly more common. The term world best was also briefly in use. The latter term is still used in athletics (track and field) to describe performances not recognized as an official world record, either because the event is a non-qualifying event (e.g. the 500 yards run) or because it does not fulfill other criteria of an otherwise qualifying event (e.g. the Great North Run half-marathon, which has an excessive gradient).'Outside of conventional sports, world records can also be set in virtually anything that is measurable, but verifying these records is often very difficult. Guinness World Records (formerly Guinness Book of Records) collects and tries to verify all kind of world records. Open Record Book is a free online record of world and local records.
