The aim of the book is to provide an introduction to the theoretical foundations, numerical methods, and applications of nonlinear optimization. The selection has been made in such a way that the practical approach to solving specific problems is adequately considered. To this end, the author examines simple models for production and inventory management problems. He explains the theoretical results using these models, discusses possible variants, improvements, and refinements of the modeling, and explores various ways to formulate such problems as nonlinear optimization problems. Additionally, he demonstrates the application of optimization software for the numerical calculation of solutions to nonlinear optimization tasks through numerous examples, while also covering the implementations of optimization methods from mathematics.