High contrast imaging opportunties abound in astronomy, and some carry such intrinsic interest that they justify considerable effort to master the technical challenges. The field has a rich history dating back to the beginnings of electromagnetic theory, and ten years ago one might have been forgiven for thinking that the topic was passé. But just within the last decade the study has fluorished with major advances on multiple fronts - scientific as well as technical. The analytical and conceptual generalization of classical coronagraphy to include complex masks and apodizations has opened a fertile field of study. Nulling in interferometry and direct imaging has developed in several promising directions, with empirical and theoretical understanding sometimes passing via different routes to arrive at firm conclusions. Critical supporting technology is developing apace, often for reasons having little to do with high contrast imaging. Thus very large telescopes, space telescopes, adaptive optics, and ultra-precision optics are all steadily advancing, and thus building a priceless technological foundation for future high contrast imaging experiments and facilities. This chapter offers a brief, simple overview, intended primarily to give a context for the many detailed technical papers in this volume.