The status of our understanding of relativistic sum rules is reviewed. The
recent development of new theoretical methods for the evaluation of these sum
rules offers hope for further advances in this challenging field. These new
techniques are described, along with a discussion of the source of difficulties
inherent in such relativistic calculations. A connection is pointed out between
certain sum rules for atomic interactions with charged particles and those for
interactions with photons.Comment: 32 pages, accepted for publication in Advances in Quantum Chemistr