The fundamental idea of the semantic web is to prepare information that would otherwise only be understandable to humans in such a way that it can be interpreted and processed by computers. To achieve this, the semantics of the content must be formally defined. The author provides a clear introduction to the semantic web, knowledge communities, and knowledge media, explaining the underlying concepts in a practical manner using the example of problem-oriented medical histories. Contents include: - A use case from clinical medicine - The concept of knowledge media - The semantic web - Designing a knowledge medium for the application scenario - Outlook. The content is structured in a way that it can be easily taught in units about the semantic web and knowledge media.