This lecture introduces the concept of metadata in geographic information systems, emphasizing the importance of documenting spatial information to ensure consistent understanding among users. It covers the scope of metadata, including source, content, and types of data, using cadastral data examples. The lecture also discusses the significance of standardization, focusing on international norms like ISO/TC 211 and the EU's INSPIRE Directive. It delves into the Swiss metadata model GM03, detailing its core and comprehensive versions. Additionally, it explores the role of metadata in facilitating data exchange, improving information search capabilities, and providing a reference framework for metadata management tools.