Since the establishment of the conductive properties of intrinsic conductive polymers, an enormous variation of basic and applied research has been carried out, including different polymers, co-polymers, blends, mixtures and composites. Until about 30 years ago all carbon based polymers were rigidly regarded as insulators. The notion that plastics could be made to conduct electricity would have been considered to be absurd. Indeed, plastics have been extensively utilised by the electronics industry for this very property. They are used as inactive packaging and insulating material. This very narrow perspective is rapidly changing as a new class of polymers known as intrinsically conductive polymers or electroactive polymers are being discovered. Consequently, ultimate understanding of physical and chemical properties of these materials has been pursued, while the applied facets have advanced very rapidly, crossing the boundaries between disciplines. Conductive polymers or, more precisely, intrinsically conducting polymers are organic polymers that conduct electricity. Such compounds may have metallic conductivity or can be semiconductors. The biggest advantage of conductive polymers is their processability, mainly by dispersion. Conductive polymers are generally not thermoplastics. But, like insulating polymers, they are organic materials. They can offer high electrical conductivity but do not show similar mechanical properties to other commercially available polymers. This book delivers information about the development of fundamentals, and about some applications of conductive polymers.