AbstractAn overview of optical networks is provided. An introduction into the area of optical networks, their abilities and characteristics and their place in today's communication technology are made. The various components that an optical network consists of are examined. These include examination of the structure and operation of optical fibres, optical transmitters and receivers, optical amplifiers and other related optical components. The various classes of optical networks—optical link networks, broadcast and select networks, wavelength‐routed networks, photonic packet‐switching networks and optical burst switching ones—are then explained. Finally, an examination of various trends in the optical networking area is made. Copyright © 2001 John Wiley & Sons, Ltd.