An umbrella is a portable device used for protection against rain or sunlight. It typically consists of a circular canopy made of waterproof fabric, supported by a framework of ribs and a central pole. When opened, the canopy expands to create a shield, keeping the user dry or shaded. Umbrellas come in various sizes and styles, including compact versions that can fit in a bag and larger ones designed for outdoor use. They are often used in conjunction with other items like raincoats and sunglasses to enhance comfort during different weather conditions.