This course introduces the essential principles of materials science, focusing on the relationship between the structure of matter and the ways in which its properties can be modified. It covers atomic and crystalline structures and their imperfections; transport mechanisms and diffusion; phase diagrams -including the iron-carbon system-; and the main hardening processes. The course also examines heat treatments, the mechanical properties of materials, and metallic alloys, along with basic production and forming methods, providing a comprehensive overview of material design, selection, and transformation in engineering.