This book is intended for use as a concepts textbook to accompany a one-semester or one-quarter introductory course on computers or microcomputers. Key features of this third edition include: emphasis on unification of computer and communications systems; revision in response to extensive instructor and student feedback; commonsense illustration program; emphasis on practicality; emphasis on ethics; use of techniques for reinforcing student learning; and up-to-the-minute material. Chapters are as follows: (1) "The Digital Age: An Overview of the Revolution in Computers and Communication"; (2) "Applications Software: Tools for Thinking and Working"; (3) "System Software: The Power Behind the Power"; (4) "Processors: Hardware for Power and Portability"; (5) "Input and Output: Taking Charge of Computing and Communications"; (6) "Storage: Foundations for Interactivity, Multimedia, and Knowledge"; (7) "Telecommunications: The Uses of Online Resources and the Internet"; (8) "Communications Technology: Hardware, Channels, and Networks"; (9) "Files and Databases: From Data Organizing to Data Mining"; (10) "Information Systems: Information Management and Systems Development"; (11) "Software Development: Programming and Languages"; and (12) "Society and the Digital Age: Promises and Challenges". Key questions are presented at the beginning of each chapter. The text is fully illustrated in color. Contains an index. (AEF)