THERE ARE THREEkinds of pottery, all of which started life as clay: Stoneware is a mixture of clays fired at very high temperatures (about 2,400 degrees); earthenware, also from a mix of clays, is often glazed with bright colors and fired at comparatively low temperatures (less than 2,000 degrees), and china, usually of one kind of clay fired at low temperatures. It is the purest and most delicate form of pottery, so fine that one can see a hand held under it.
Pottery is an ancient craft, first worked at about 7000 BC in Egypt. The Egyptians started glazing their wares about 3000 BC, and by 1600 BC the Cretans had refined the art to include curved figures and depictions of animals. About 1500 BC, the Chinese were using the pottery wheel to make more precisely shaped items.
Today the term pottery is used to describe the function of the finished piece rather than the characteristics of the raw material. Pottery refers to useful items--cups, vases, plates--and includes stoneware and earthenware. Ceramics is used to describe more decorative pieces, such as animals, figures--and also vases. In all cases and regardless of name, the shaped clay can (and in some cases should) be glazed before being fired in a large oven, or kiln, a process that sets the shape and finish. (Terra cotta, a kind of earthenware, is fired but not glazed.) Glazing adds subtle color (or no color), but, more important, it adds a finish that seals the clay when fired at hot-enough temperatures and makes the object water- and oven-proof. Ceramic items can be painted as well as glazed.