Like underwear briefs, swim briefs feature a "V-shape" front and a solid back providing form-fitting coverage. They are usually worn below the lower waist, but some of them can be worn at the waist (resembling the briefs worn by some professional wrestlers). They are generally secured by thin banding at the upper thighs and either a drawstring around the waist or an elasticized waistband. Swim briefs are most often made of a nylon and spandex (Lycra) composite, while some longer lasting suits are made from polyester and still others from other materials. Most swim briefs have a beige or white front lining made of a similar fabric.
The popularity of swim briefs as casual beachwear and swim wear varies throughout the world. In mainland Europe, Brazil, China and Japan, swim briefs are very popular among male swimmers and beach goers. In English-speaking countries, the roomier and less revealing trunks or board shorts are the more common choice of suit for recreation, although swim briefs are always seen to some extent. Reasons swim briefs are chosen for recreation include style, ease of movement in the water, sunshine exposure, quick drying time, and the ability to be worn under pants or shorts.
Briefs worn for competitive and recreational swimming are manufactured in standard sizes and in waist measurements. They are available in a wide variety of solid colors and patterned designs.
The most common racing suit styles are 1.5 inch to 3 inch paneled briefs (as measured by the length of the suit's side panel). The racing suit's main function is to reduce the drag of an athlete in water, thus improving his time. For this reason racing suits are made of materials that hug the body, minimize friction and minimize water retention. Spandex (Lycra) suits generally produce less drag, but are also more vulnerable to prolonged exposure to chlorine than nylon. Therefore, nylon suits are preferred for training and practice, where the increased durability is required for the long periods of usage and the extra resistance brings a training benefit. Lycra suits (and composite hi-tech swimwear fabrics) are preferred for actual racing. In water polo and sometimes in diving, suits may have panels greater than 3 inches.
Water polo players generally wear racing suits. This is to minimize the fabric available to grabbing and pulling by opponents - actions that are illegal yet often happen underwater - while not compromising the strength of the fabric. High-level players wear specialized suits, usually of a very tight fit and made of thicker, tougher and more slippery fabric, intended to thwart pulling and grabbing during rough play; they often wear two suits on top of each other.
Suits less than 1.5 inches wide at the hips, sometimes called bikinis, are less common for sporting purposes and, unlike the racing style, are not designed specifically for drag reduction. Bikinis are most often worn for recreation, fashion, and sun tanning where minimal suit coverage is preferred. An extremely brief version of this style, known as the posing brief, is the standard for competitions in the sport of bodybuilding.