This comprehensive monograph deals with self-timing in digital systems. It combines in one volume models of asynchronous processes and design of logical circuits - combinational and sequential. This feature is rather unique in textbooks which focus usually on only one of these fields. The book is devoted to circuits whose behaviour does not depend on the values of element delays. Such circuits are also called aperiodic (in Russian texts), Muller circuits or speed-independent circuits. The self-timing property is based on the idea of an indication of transition process completion. Although it requires the redundancy as compared with clocked circuitry, the avoidance of central clock may be profitable in VLSI design, especially if the circuits are independent of gate- as well as wire-delays. On the other hand, there exist circuits asynchronous by their nature, like arbiters and communication interfaces. The material is not limited to one particular approach to process modelling and circuit design. It is based on fairly studied history of the subjects. The intention of the authors was to describe fundamentals of the three basic phases of designing self-timing circuits: 1) modelling (i.e. algorithm of functioning), 2) abstract synthesis (i.e. encoding of states and signals), 3) structured synthesis (i.e. constructing an implementation in a given element basis). The chapter on modelling introduces the general model of a descriptive asynchronous process, from which four specific models are derived - Petri nets, Muller diagrams, parallel asynchronous flowcharts and asynchronous state machines. The chapter on self- synchronizing codes gives a systematic review of encoding techniques for signals transmitted along parallel data lines with a particular emphasis on totally asynchronous design requirements. The various chapters describe methods for designing circuits from asynchronous processes specifications. One of the goals is modular design - therefore composition of asynchronous processes and circuits is discussed. An important issue is analysis of asynchronous processes and circuits - also covered in the book. A number of topics and examples dealing with specific circuits include basic implementations like flip-flops, counters, registers etc., implementation of communication protocols, as well as extensive study of anomalous behaviour of arbiters. The overall design methodology leads to efficient error-detection mechanisms and fault-tolerant organization. The rich bibliography given in the book contains about 350 items published till the year 1986, about half of them are published in the Soviet Union. This textbook may be very useful for advanced courses in digital systems design.