The book "Introduction to Mathematical Logic" offers a comprehensive introduction to the fundamentals of mathematical logic and its applications. It addresses central questions such as the nature of mathematical proofs, their justification, and the limits of provability. The authors, Wolfgang Thomas, Heinz-Dieter Ebbinghaus, and Jörg Flum, present the results of mathematical logic systematically, with a focus on first-order logic. The reading is suitable for anyone with a certain familiarity with mathematical thinking, although no special prior knowledge is required. In the current edition, solution sketches for the exercises have also been added to enhance understanding. This revised edition also includes new content on key results that are significant for logic and computer science.