This third edition of Discrete-Time Signal Processing is a major revision of our second edition. The new edition is in response to changes in the way the subject is taught and to changes in scope of typical courses at the undergraduate and first-year graduate level. It continues the tradition of emphasizing the accessibility of the topics to students and practicing engineers and focusing on the fundamental principles with broad applicability. A major feature of the new edition is the incorporation and expansion of some of the more advanced topics, the understanding of which are now essential in order to work effectively in the field. Every chapter of the second edition has undergone significant review and changes, one entirely new chapter has been added, and one chapter has been restored and significantly updated from the first edition.