Vitrified pottery with a white, fine-grained body that is usually translucent, as distinguished from earthenware, which is porous, opaque, and coarser. Porcelain is a fine form of pottery which is fired to a very high temperature in order to vitrify the clay. The name is derived from Portuguese 'porcellana' (little pigs, name given to cowrie shells by early traders). Porcelain was developed by Chinese from a long tradition of making stoneware in white clay. In the T'ang Dynasty (618-906 AD) came proto-porcelains, followed by true porcelain in the Sung Dynasty (960-1279 AD). The three main types of porcelain are true, or hard-paste, porcelain; artificial, or soft-paste, porcelain; and bone china.