Abstract. Lasers have become ubiquitous devices, not only in mechanisms that surround us in our daily lives but also as essential laboratory tools throughout the disciplines of physical and biological sciences. For many of these purposes it is only the near-monochromatic properties, or the directional properties, that are used. But the coherence properties have become increasingly valuable. I will discuss laser coherence as it is used for producing, in individual atoms or molecules, various manipulations of the internal structures that, according to quantum theory, underly the properties of such microscopic entities. Whereas the first exploitation of coherence aimed simply to produce excitation of preselected quantum states (a technique of interest in studies of chemical reaction dynamics and analytical chemistry), more recent interest has centered on creating coherent superpositions - a purely quantum mechanical notion that has application in such newly emerging technologies as quantum information processing.

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