This lecture covers the use of open-source tools like IfcOpenShell to work with Building Information Models (BIM). It explains how to read, write, and modify BIMs using IFC, a digital language for the built environment. The lecture also delves into the robust geometry capabilities, 2D drawing generation, and the ecosystem of tools available. Additionally, it explores the process of authoring BIMs using IfcOpenShell, providing a comprehensive overview of the functionalities and benefits of this open-source toolkit.