Conducting polymers, represented by polyaniline and polypyrrole, are interesting objects suited for interdisciplinary studies. They are easily prepared by oxidative polymerization producing cheap and versatile materials suitable for many applications. An increasing number of scientific papers dealing with the topic reflects the growing interest in conducting polymers, their processing as well as in their specific forms, like thin films and colloidal dispersions. The intrinsic colour and conductivity of these polymers, in connection with their organic and macromolecular nature, predetermine their links to the semiconductor physics, physical and organic chemistry and to analytical sciences. Composites based on conducting polymers are interesting for materials science. The range of potential uses covers simple and cheap microelectronic parts, electrochromic devices, electromagnetic shielding, analytical separations, marker particles and sensors. The topical research field expands to new and often unexpected directions.