The discovery of the fullerene molecule C60 by Kroto, Heath, and Smalley in 1985 and the subsequent discovery of carbon nanotubes by Iijima in 1991 have launched entirely new fields of materials research and development. Carbon nanotubes are single molecules that can extend to lengths approaching 0.01 mm, and they are particularly important since they bridge the nanoscopic and macroscopic length scales. The physical properties that derive from this extended one-dimensional system have changed the way we think about materials for R&D activities as diverse as quantum transport in one-dimension and functionalizing structural materials in automobiles. Here we review the key developments of the science of carbon nanotubes and outline promising technology areas. © 2005 Lucent Technologies Inc.