These introductory survey lectures, the result of a 1984 AMS Short Course, focus on the algorithmic problems arising in the construction and utilization of large-scale information systems. Addressed to both mathematicians and computer scientists, the lectures require a background in the methodologies of discrete mathematics, in particular the elements of algebra, combinatorics and graph theory, discrete probability, logic and the theory of computation. All of the articles either are of high research value or survey profound themes in current research. They cover the two fundamental aspects of the field, i.e., database systems and communication networks.An overview of database architectures, the theory of data dependencies, and transaction management are provided, respectively, by the articles of Jacobs, Fagin and Vardi, and Garcia-Molina. Chung evaluates problems in the design of communication networks. Miller's discussion of data compression algorithms links current research to classical information theory. Finally, Tuzhilin describes a general framework evolved in the Soviet Union for modelling problems of information processing.