This book highlights the fundamental concepts related to 57Fe Mössbauer spectrometry, useful for graduate students and researchers. The first three chapters present essential topics related to nuclear, quantum mechanics and magnetism. The final parts of the book focus on the fundamentals and applications of 57Fe Mössbauer spectrometry. As Mössbauer spectrometry is used by students and researchers in various disciplines, this book presents the essential aspects in the relevant subject areas. The Mössbauer parameters of Fe-based alloys, ferrimagnetic, antiferromagnetic and superconducting materials, as well as applications in earth sciences, life sciences and extraterrestrial studies, are covered.