1. Women's swimsuit
1.1 One-piece swimsuits
1.1 One-piece swimsuits

tank suit, leotard or simply one-piece: probably the most common form of one-piece swimsuit, the tank suit form is inspiration for the subsequent creation of the tank top as a mainstream article of clothing. The name "tank suit" is derived from the term swimming tank, an obsolete term for what is now called a swimming pool.
monokini: a term used for different styles of one-piece swimsuits inspired by the bikini style. Most commonly, a monokini is a bikini bottom without the corresponding top, worn by women, that leaves the breasts bare. Sling bikinis are sometimes, though not often, referred to as monokinis.
thong swimsuit: One-piece swimsuit with thong back, buttocks exposed, otherwise ordinary
sling bikini: also known as a "suspender bikini", "suspender thong", "slingshot bikini" or just "slingshot". The slingshot is a one-piece suit which provides as little, or even less, coverage (or as much exposure) as a bikini. Usually, a slingshot resembles a bikini bottom, but rather than the straps going around the hips or waist, the side straps extend upwards to cover the breasts and go over the shoulders, leaving the entire sides of the torso uncovered, but the nipples and pubic area covered. Behind the neck, the straps join and reach down the back to become a thong.
Pretzel suit: a single-piece suit similar to a sling bikini, but the straps encircle the torso around the bottom of the ribcage, forming a very high-sided bikini bottom; instead of the straps passing over the neck and down the back, they simply encircle the neck, joining the straps which pass around the midriff.
other types include stringbodys, halter-necks, maillots and plunge fronts.
1.2 Two-piece swimsuits
bikini Thong, T-back, or G-string
tankini (A tank top combined with a bikini bottom)
Freedomware, a two-piece suit that sits on the hip when folded up. (Can be worn by skinny dipers)
2. Men's swimsuit
boardshorts or swimming shorts or trunks (boardshorts are not referred to as trunks in Britain). Most french swimming pools forbid these for sanitary reasons.
speedos or briefs (trunks in Britain)
jammer(s): a type of men's swimwear worn primarily by competitive athletes to obtain speed advantages. They are made of nylon and lycra/spandex material and have a form fitting design to reduce water resistance. They provide moderate coverage from the mid-waist to the area above the knee, somewhat resembling compression shorts worn by many athletes. They provide greater leg coverage than speedos or competitive briefs, although they also have slightly more water resistance.
Tangas, thongs, t-backs and g-strings.

(From Wikipedia, the free encyclopedia)