Plastic optical fibers (POF) have been overshadowed in the last decade by the success of glass optical fibers. When people hear of optical fibers, they immediately think of glass. Few people, including professionals in the business, know about POFs, which predate those made of glass. Because glass fibers have certain advantages, they have dominated the market, while POFs have remained largely in the background. POFs had been relegated to low bit rate and short distance applications. However, recent technological advances and the emergence of new applications in the automotive, avionics, consumer electronics, and short-distance interconnect industries have propelled POF into the limelight as a lower cost alternative to glass fiber or copper at medium distances and bit rates of 40 Gbps. This chapter reviews the history of POF, the technological developments, emerging applications, commercial activities, and research and education centers around the world.