Containing the latest, groundbreaking discoveries in the field, this text outlines the basics of Einstein's theory of gravity with a focus on its most important astrophysical consequences, including stellar structures, black holes and the physics of gravitational waves. Blending advanced topics - usually not found in introductory textbooks - with examples, pedagogical boxes, mathematical tools and practical applications of the theory, this textbook maximises learning opportunities and is ideal for master and graduate students in Physics and Astronomy.Key features: Provides a self-contained and consistent treatment of the subject that does not require advanced previous knowledge of the field. Explores the subject with a new focus on gravitational waves and astrophysical relativity, unlike current introductory textbooks. Fully up-to-date, containing the latest developments and discoveries in the field.