Current trends in research and development of components for optical communication are reviewed. Emphasis is placed on active components for fiber-optic systems which have undergone recent major advances. Basic properties of optical fibers and recent technological improvements in splices, connectors, and source/detector-fiber couplers are presented first. This background information serves as a basis for describing recent developments in optical sources (e.g., device reliability, LED's and laser diodes) and photodetectors. Developments in both the 0.8-0.9-µm and 1.0-1.7-µm wavelength regions are covered. Also surveyed are results of research in areas of potential interest for optical communications: novel fiber-optic components, integrated optics (sources and modulators/switches), novel device fabrication methods, and integration of optical components.