The extraordinary ability of the chemical element carbon to combine with itself and other chemical elements in different ways is the basis of organic chemistry and of life. This chemical versatility also gives rise to a rich diversity of structural forms of solid carbon. This introductory chapter is an attempt to survey the very wide range of carbon materials that is now available with emphasis on chemical bonding and microstructure. The materials reviewed include: (i) crystalline forms of carbon: diamond, graphite, Fullerenes and carbynes; (ii) amorphous carbon films and diamond films; (iii) carbon nanoparticles, including carbon nanotubes; (iv) engineering carbons with moreor- less disordered microstructures based on that of.