MAGNETOELECTRONICS, SPIN ELECTRONICS, AND SPINTRONICS are different names for the same thing: the use of electrons' spins (not just their electrical charge) in information circuits. One magnetoelectronic device is the magnetic hard drive based on the giant magnetoresistance (GMR) effect. In a GMR material, consisting of a stack of alternating layers of magnetic and nonmagnetic atoms, a small magnetic field can produce a large change in electrical resistance. Already a billion dollar business, GMR read heads will boost disk drive densities from 1 to 20 Gbits, and GMR might be incorporated into random access memory units as well (Gary Prinz, Science, 27 Nov 1998). The latest demonstration of spin versatility is the organized movement of a herd of spins over a lateral distance of 100 microns. In an experiment at UC Santa Barbara, David Awschalom first aligned the spins of a swarm of electrons and then nudged them across a semiconductor strip without the spin bunch falling apart. Such coherence will be necessary if spin currents are to transport information from place to place, particularly in quantum computers. (Nature, 14 Jan 1999.)