This article summarizes current applications and the future potential of highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT). The main focus of the article is a water dispersed complex of PEDOT with poly(styrenesulfonic acid) (PSS) as the counter-ion. The availability of PEDOT:PSS as an ink allows many facile ways of solution processing. The basic chemical and physical properties of the PEDOT:PSS complex are discussed to show the fundamentals that allow for the use of PEDOT in transparent conductive applications. Due to the increase in conductivity and transparency of the PEDOT:PSS complex in recent years, this versatile material now has reached the requirements for current devices such as displays, touch screens, and solar cells, and offers an alternative to inorganic transparent conductive oxides. Further advantages of this polymer are the ductility, use in low-cost production processes such as printing, safe handling, and availability on a large scale.