The aim of this book is to describe and illustrate the main features of the Ada language and to show how they are used. The designers of Ada have taken many good features of earlier languages, extended or improved them where necessary, and added other elements to produce a language which is specifically intended to support software engineering. The language has many uses, due to its concurrency and low level features, such as in the military environment. Compilers and software tools, such as an interactive dialogue development system can be implemented and maintained more easily in Ada than in other languages. Ada is also equally suited to data processing applications. This book is be of general appeal to all those who wish to learn about Ada.