This SpringerBrief reviews exhaustively the representative research on the Technology Acceptance Model (TAM) from its first appearance thirty years ago until now, also identifying possible directions for future research. TAM is a theory from the Information Systems (IS) discipline for explaining, predicting, and improving user acceptance of information technology (IT). The findings revealed that TAM is a leading scientific paradigm and a credible model for facilitating assessment of diverse technological deployments. TAM’s core variables, perceived usefulness and perceived ease of use, have been proven to be the principal causal mediators between objective IT design characteristics of technology adoption and use. The introductory chapter “Once upon a TAM” focuses on the challenging search of a user acceptance crystal ball. The chapter “Evolution of TAM” provides thorough insight into the proliferation and consolidation of behavioural intention models, factors that affect behavioural intention as well as TAM moderators. A systematic review of TAM is reported in the chapter “Revolution of TAM”. Besides a meta-review of existing reviews and meta-analysis, a narrative review of the representative studies that underlie research on TAM is presented, offering a clear vision of the TAM universe. The chapter “Where do we go now?” concludes this book In order to equip new TAM researchers to handle their own studies, the book also includes a number of actionable principles and guidance about how to test the validity of TAM when applied to a particular technology. This comprehensive overview of TAM is considered a valuable source of information for readers, researchers and practitioners particularly those new to the field.