Underwear is clothing worn underneath your outer clothes, next to your skin. It includes items like undershirts, underpants, and similar garments. The main purposes of underwear are comfort, hygiene, and protection: it helps keep your outer clothes cleaner, provides an extra layer between your body and rougher fabrics, and helps you stay comfortable throughout the day.

Different types of underwear serve different purposes. Athletes might wear special athletic underwear that wicks away sweat during games or practice. In cold weather, people wear thermal underwear, sometimes called long underwear, to stay warm. In ballet and other dance forms, performers wear specific types of underwear designed to work with their costumes and allow freedom of movement.

Underwear is a normal, practical part of getting dressed every day, but it's considered private clothing, which is why people don't typically talk about it in detail or display it publicly. Washing underwear regularly and replacing it when it wears out are part of basic hygiene.