Conducting polymers have received much attention since the early 1980s. They have inherent electrical conductivity and are different from other polymeric materials, which are made conducting by blending polymers with carbon or metal powders. In particular, the demonstration that films of conducting polymers on electrodes can be switched electrochemically between the insulating and conductive state with a corresponding change in the electrical, optical, and chemical properties attracted the attention of investigators from various disciplines. The brief overview below presents selected examples to describe the structural characteristics and properties of conducting polymers.