A bed is a large piece of furniture (or a location) used as a place to sleep, and as a primary place for relaxation and sexual activity. In many cultures it is considered the most important piece of furniture in the home.
Today's beds usually consist of a mattress placed on top of a box spring inner-sprung base. The box spring is a large mattress-sized box containing wood and springs that provide additional support and suspension for the mattress.
The box spring will often lie on a bed frame (which lifts the mattress/mattress-box spring off the ground) or on slats (usually made of 1" x 4" wood).
A "headboard", "side rails", and "footboard" or "front rail" will complete the bed.
"Headboard only" beds often incorporate a dust ruffle, bed skirt, or valance sheet to hide the bed frame.
For greater head support, most people use a pillow, placed at the top of a mattress. Also used is some form of covering blanket to insulate the sleeper, often bed sheets, a quilt, or a duvet.
Also, some people prefer to dispense with the box spring and bed frame, and replace it with a platform bed style.