The book "Sets - Numbers - Number Ranges" is aimed at first-semester mathematics students and imparts fundamental knowledge covered in introductory lectures. It addresses the most important number sets, from natural numbers to complex numbers, and introduces the fundamental concepts of set theory and functions. A variety of examples and counterexamples enhance the understanding of mathematical terms. Additionally, the book includes a chapter with approximately 300 exercises that support the learning process and promote the application of the concepts learned. This work is therefore a valuable resource for anyone looking to engage with the fundamentals of mathematics.