As a programming language, ATS is both syntax-rich and feature-rich. This book introduces the reader to some core features of ATS, including basic functional programming, simple types, (recursively defined) datatypes, polymorphic types, dependent types, linear types, theorem-proving, programming with theorem-proving (PwTP), and template-based programming. Although the reader is not assumed to be familiar with programming in general, the book is likely to be rather dense for someone without considerable programming experience.