Solid materials have been conveniently grouped into three basic classifications:met-
als, ceramics, and polymers.This scheme is based primarily on chemical makeup and
atomic structure, and most materials fall into one distinct grouping or another,
although there are some intermediates. In addition, there are the composites, com-
binations of two or more of the above three basic material classes.A brief explana-
tion of these material types and representative characteristics is offered next.Another
classification is advanced materials—those used in high-technology applications—
viz. semiconductors, biomaterials, smart materials, and nanoengineered materials;