Questions about swimming in the context of sport. When referencing part of a multisport event, consider tagging for "triathlon" or "ironman" instead.

Questions about swimming in a recreational or survival context are off-topic, see this meta discussion.

Competitive swimming is generally classed according to gender, the stroke or strokes employed, and the distance traveled. The four major strokes in competitive swimming, in order of their use in men's "medley" events (where swimmers perform each of the four strokes in one race), are:

  • Butterfly - the swimmer faces down into the water and uses a simultaneous overhead circling arm motion, combined with a simultaneous straight-leg "dolphin kick". Typically the most physically demanding stroke, requiring swimmers to literally launch their upper body out of the water to bring their arms forward, it is the first stroke of individual medleys or medley relays.
  • Backstroke - the swimmer faces up out of the water (on their back) and uses an alternating overhead arm stroke, similar to the crawl but in reverse, combined with an alternating straight-legged "scissor kick".
  • Breaststroke - the swimmer faces down into the water and uses a simultaneous flat arm motion pushing forward through the water and then pulling back to the swimmer's sides, combined with a simultaneous bent-leg "frog kick". Typically the slowest stroke (the men's world record 200m time is over two minutes, almost 30 seconds slower than the record 200m freestyle time) due to high drag and lack of a continuous propulsion motion.
  • Crawl (Freestyle) - the swimmer faces down into the water and uses an alternating overhead circling arm motion to reach forward and push backward, combined with a "scissor kick". Technically "freestyle" swimming events allow the swimmer to choose any stroke they like, but the crawl is almost universally chosen by swimmers in these events (as it is the fastest, by a margin of over 10 seconds over the backstroke or butterfly) and so has become synonymous with "freestyle". This is the "anchor" or last leg of a medley event.

Common race distances for adult swimmers are based on lengths of a 50m Olympic swimming pool (often called a "long course"), and include 50m, 100m and 200m individual events in all four strokes, 400m "medleys", relays and individual freestyle events, 800m relays and individual freestyles, and 1600m individual "endurance" freestyle races. Junior swimmers often swim in a "half-Olympic" or "short course" pool 25m in length; at the junior level distances are typically 25m and 50m single-stroke sprints, and 100m and 200m medleys, relays and endurance events. In the US, yards are sometimes used as the distance measure instead of meters; the distances are similar but a yard is slightly shorter than a meter (by about 3 inches), so a 200yd event would be 182m. Olympic events, and pools built to Olympic standards, are always in meters.

Relay events involve teams of four swimmers each swimming one "leg" (two or four lengths) of the full event, and at the adult level are commonly 4x100 (400m total distance) medley and freestyle, and 4x200 (800m total) freestyle. At the junior level, 4x25 and 4x50 freestyle and medley relays are also seen.

Swimming competitions are held at virtually all age and skill levels, however it is rare to see a competitive swimmer over the age of 30 due to the high level of physical demand and training time required, and most current records were set by swimmers under the age of 25. Junior swim teams introduce swimmers to competitive meets as young as 4 or 5 at local meets, and continuing to age 17, with high schools and colleges sponsoring swim teams up to college graduation age, and national teams sponsoring swimmers as long as they can remain competitive at the international level.