Building design is the structured process of shaping the functional, spatial, and technical systems that define a construction project. It integrates architectural, structural, mechanical, and electrical disciplines into a coordinated whole, ensuring that all systems perform safely, efficiently, and in alignment with client requirements, regulations, and environmental conditions. This section introduces users to the holistic nature of building design—emphasizing the importance of interdisciplinary coordination, phased development, and standards-based decision-making. It outlines the project lifecycle from concept through construction documents and bidding, highlighting the roles of each discipline and the shared need for collaboration at every stage. Users are guided to understand how design strategies evolve over time and how key decisions affect performance, sustainability, and constructability. This foundation sets the stage for the specialized domains that follow, helping users contextualize each discipline’s contribution within the broader framework of integrated building system design.