Body liners are essential for personal hygiene and comfort, absorbing moisture, preventing stains, reducing friction, and combating odors. They can be used in various areas, including armpits, groin, and feet, and are available in different types (underarm liners, underwear liners, socks with built-in liners) and materials (cotton, synthetics, disposable). Liners are particularly beneficial during exercise, hot weather, travel, social events, and for individuals with medical conditions.