Since their discovery 16 years ago, the field of intrinsically conducing polymers — “synthetic Metals” — has developed at an unexpectedly rapid rate. The concept of “doping” is the unifying theme which distinguishes this class of organic polymers — “conducting polymers” — from all others. Doping results in dramatic electronic and magnetic changes with a concomitant increase in conductivity to, or approaching, the metallic regime. Doping phenomena and the chief types of dopable organic polymers are described with particular emphasis on polyaniline, which is now probably the most actively-studied conducting polymer. It has been commercialized on a relatively large scale and presently appears to be the leading conducting polymer for technology. It shows considerable promise for electromagnetic interference (EMI) shielding and as a gas separation Membrane, and is currently used in commercial rechargeable batteries. Polypyrrole is used commercially in capacitors and as an electrically conductive coating on conventional fabrics. Additional potential uses of conducting polymers such as light-emitting diodes, electrochromic windows, chemical sensors, etc. are also described briefly.