A pillow is a device used to support the head and neck during sleep or rest. Pillows come in various sizes, shapes, and materials, and their primary purpose is to maintain the natural alignment of the spine and reduce pressure on the neck and shoulders. The filling materials of pillows can include feathers, synthetic fibers, memory foam, latex, and even water or air. Choosing the right pillow depends on factors such as sleeping position, personal preferences, and an individual’s health conditions.