What's an Underwear ?
Underwears are items of clothing worn beneath outer clothes, usually in direct contact with the skin, although they may comprise more than a single layer. They serve to keep outer garments from being soiled or damaged by bodily excretions, to lessen the friction of outerwear against the skin, to shape the body, and to provide concealment or support for parts of it. In cold weather, long Underwear is sometimes worn to provide additional warmth. Special types of Underwears have religious significance. Some items of clothing are designed as Underwears, while others, such as T-shirts and certain types of shorts, are appropriate both as undergarments and as outer clothing. If made of suitable material or textile, some Underwears can serve as nightwear or swimsuits, and some are intended for sexual attraction or visual appeal.
Underwears are generally of two types, those that are worn to cover the torso and those that are worn to cover the waist and legs, although there are also garments which cover both. Different styles of Underwears are generally worn by females and males. Underwears commonly worn by females today include bras and panties (known in the United Kingdom as knickers), while males often wear classic briefs, boxer briefs, or boxer shorts. Items worn by both sexes include T-shirts, sleeveless shirts (also called singlets or tank tops), bikini underpants, thongs, G-strings and T-fronts.
Source : Undergarment Wikipedia