Historically, fibers are known to be relatively passive materials and are used primarily in textiles. Today, however, fibers with a range of functionalities such as electrical and thermal conductivity, superparamagnetic properties, temperature regulation, energy harvesting, and biomedical capability provide many possibilities. Most man-made fibers today are derived from petroleum, but there is increasing emphasis on making fibers biorenewable. Fibers are also the strongest structural materials available today. Different fiber fabrication technologies, available properties, and some near-term future prospects are discussed.