Indian Trigonometry was developed as a powerful mathematical tool for Siddhāntic Astronomy. The book, Bhāratīya Trikoṇamiti Śāstra (Hindu Trigonometry) deals with all the relevant topics of Indian trigonometry, including trigonometrical identities and other formulas, trigonometrical tables, methods of interpolation and trigonometrical series, etc. The subject matter is discussed in eleven chapters divided into 80 sections and 50 sub-sections, involving translations of 250 verses spread over in 38 classical Sanskrit works and based on 42 research articles published in 16 research journals. By including material of the late Āryabhaṭa School or Kerala Āryabhaṭa School, the author has made the book comprehensive and up-to-date. Indeed, the book is fascinating and significant. It is a definite contribution in the study of the history of Indian mathematics. The book is the English version of the Kannada book of the same title.