This book provides a comprehensive and accessible introduction to software engineering, ranging from the pillars of classical theory to innovations in modern practices, including Essence, the first formal descriptive theory of software engineering. Structured in interconnected sections, the text explores historical foundations, such as requirements analysis and traditional development models, and integrates them with contemporary approaches, including agile methodologies, DevOps, and artificial intelligence. Particular attention is given to software project management, offering valuable tools for planning, controlling, and ensuring the success of software development projects. Software testing, essential for ensuring quality and reliability, is addressed in depth, with practical strategies and validation and verification techniques. Finally, the book introduces two standard graphical languages for software modelling: UML (Unified Modelling Language) and BPMN (Business Process Modelling Language). These two tools are presented in a way that facilitates their understanding and application in the various stages of development. Designed to educate and inspire anyone who wants to approach or delve deeper into the world of software engineering, this text represents a theoretical and practical path to understanding and mastering a discipline that is constantly evolving. The book, which draws on the author's experience of almost forty years of work and thirty years of teaching in the field, is primarily intended for university students of computer science or engineering, but can also be used by secondary school students or students from other university faculties interested in learning more about the subject. Ultimately, it can be understood by anyone, even those without a solid background in computer science, to gain a deeper understanding of and explore what software engineering entails.