Records

Start of the 4x100 meters relay in the Watercube. Beijing, August 11, 2008.

The foundation of FINA in 1908 signalled the commencement of recording the first official world records in swimming. At that time records could be established in any swimming pool of length not less than 25 yards, and records were also accepted for intermediate distance split times from longer distance events. Today World Records will only be accepted when times are reported by Automatic Officiating Equipment, or Semi-Automatic Officiating Equipment in the case of Automatic Officiating Equipment system malfunction.

Records in events such as 300 yd, 300 m, 1000 yd, and 1000 m freestyle, 400 m backstroke, and 400 m and 500 m breaststroke were no longer ratified from 1948. A further removal of the 500 yd and 500 m freestyle, 150 m backstroke, and 3×100 m medley relay from the record listings occurred in 1952.
In 1952, the national federations of the United States and Japan proposed at the FINA Congress the separation of records achieved in long-course and short-course pools, however it was four more years before action to came into effect with Congress deciding to retain only records held in 50 m pools as the official world record listings.
By 1969 there were thirty-one events in which FINA recognised official world records – 16 for men, 15 for women – closely resembling the event schedule that was in use at the Olympic Games.
The increase in accuracy and reliability of electronic timing equipment led to the introduction of hundredths of a second to the time records from 21 August 1972.
Records in short course (25 m) pools began to be officially approved as "short course world records" from 3 March 1991. Prior to this date, times in short course (25 m) pools were not officially recognised, but were regarded a "world best time" (WBT). From 31 October 1994 times in 50 m backstroke, breaststroke, and butterfly were added to the official record listings.
FINA currently recognises world records in the following events for both men and women.

• Freestyle: 50 m, 100 m, 200 m, 400 m, 800 m, 1500 m
• Backstroke: 50 m, 100 m, 200 m
• Breaststroke: 50 m, 100 m, 200 m
• Butterfly: 50 m, 100 m, 200 m
• Individual medley: 100 m (short course only), 200 m, 400 m
• Relays: 4×100 m freestyle, 4×200 m freestyle, 4×100 m medley