A bed is a piece of furniture or location primarily used as a place to sleep, but can serve other functions, such as providing a place for sexual intercourse (alone or with others) or for jumping (especially children), relaxation, etc.
Beds come in a wide array of shapes and sizes. Early beds were little more than piles of straw or some other natural materials. An important change was raising them off the ground, to avoid drafts, dirt, and pests.