This review article focuses on conducting polymers and their applications. Conducting polymers (CPs) are an exciting new class of electronic materials, which have attracted an increasing interest since their discovery in 1977. They have many advantages, as compared to the non-conducting polymers, which is primarily due to their electronic and optic properties. Also, they have been used in artificial muscles, fabrication of electronic device, solar energy conversion, rechargeable batteries, and sensors. This study comprises two main parts of investigation. The first focuses conducting polymers (polythiophene, polyparaphenylene vinylene, polycarbazole, polyaniline, and polypyrrole). The second regards their applications, such as Supercapacitors, Light emitting diodes (LEDs), Solar cells, Field effect transistor (FET), and Biosensors. Both parts have been concluded and summarized with recent reviewed 233 references.