A
mouse pad is a
cloth or
plastic covered pad, usually made of
foam, that a computer
mouse is used on. Mouse pads come in many shapes and sizes; most of them have interesting pictures on them or a
company logo.
Mouse pads were originally a necessity; steel balls in mice would mar the working surface rather badly. Modern mice don't damage the work surface much and track fine without a pad in most cases, but people still like to use them. Sometimes mousing is more comfortable on a pad; sometimes people like to make a statement with the design they choose to have on their pad.