This chapter is a summary of the state of the art of concentrating photovoltaic (CPV) systems, discussed from several viewpoints. It begins with an abbreviated history of the technology, then continues to a discussion of the characteristics, market, and system design. A short piece on future trends concludes. Because of its complex nature, this chapter is limited to a qualitative introduction to this interesting and prospective field and assumes a general familiarity with photovoltaics (PVs).