For many years atomic physicists had used quantum mechanics very successfully to calculate energy levels, cross sections and other practical quantities, and for the most part, left the philosophical issues of interpretation to others. But after the work of Bell in the 1960's showed that the peculiarly nonlocal nature of quantum correlations could be tested in the lab, a number of atomic physicists turned to the experimental study of entanglement and quantum measurement. A second phase began at the start of the 1990's when it was realized that correlations and quantum superpositions could be exploited in quantum information processing and secure communication. This has led to an explosive growth of the subject over the past 10 years, fuelled by the long-term prospects of quantum computing and the nearer goal of quantum cryptography. We review some of these developments in this chapter.