This book offers an introduction to the development and simulation of Modelica models for engineering applications. The target audience are bachelor's or master's level students, interested in modeling and simulation, and with a background in both physics and numerical methods. The book is structured into three parts. The modeling methodology and the Modelica features for continuous-time modeling are discussed in the first part of the book. The simulation of continuous-time Modelica models is addressed in the second part of the book. The third part of the book is devoted to discuss hybrid modeling and simulation in Modelica.The modeling methodology, the Modelica language features, and the use of modeling environments are explained through examples. This facilitates the use of this book in the context of student-centered learning strategies, such as problem-based learning, and project-based learning.Alfonso Urquía and Carla Martín are professors in the Departamento de Informática, UNED