Logic programming provides new ways of solving problems by computer, and offers opportunities for concurrent processing. The declarative style of logic programming is contrasted with the imperative style of conventional programming languages. A simple example of a logic network is used to draw out the distinction, and is followed by a review of the corresponding execution sequence. The operations of variable binding and unification are discussed in detail. The Syracuse unification machine, a coprocessor for a logic programming system, has been designed to carry out these operations efficiently with the aid of concurrent processing units and content-addressable memory.