Meteorites are being used for a variety of extraterrestrial studies. They include the oldest solar system materials available and sample a wide range of parent bodies, some primitive, some highly evolved. Meteorites carry decipherable records of certain solar and galactic effects and yield otherwise unobtainable data about the genesis, evolution, and composition of smaller bodies in the solar system and, by inference, of the earth and other planets, their satellites, and the sun. They also provide an important body of “ground truth,” in a chemical and physical sense, critical to interpreting planetary data obtained by remote sensing.