At its very core multimedia information retrieval means the process of searching for and nding multimedia documents; the corresponding research field is concerned with building the best possible multimedia search engines. The intriguing bit here is that the query itself can be a multimedia excerpt. This course examines the full matrix of a variety of query modes versus document types. The course discusses techniques and common approaches to facilitate multimedia search engines: metadata driven retrieval; piggyback text retrieval where automated processes create text surrogates for multimedia; automated image annotation; content-based retrieval. The latter is studied in great depth looking at features and distances, and how to effectively combine them for efficient retrieval, to a point where the participants have the ingredients and recipe in their hands for building their own multimedia search engines. Supporting users in their resource discovery mission when hunting for multimedia material is not a technological indexing problem alone. We look at interactive ways of engaging with repositories through browsing and relevance feedback, roping in geographical context, and providing visual summaries for videos. The course emphasises state-of-the-art research in the area of multimedia information retrieval, which gives an indication of the research and development trends and, thereby, a glimpse of the future world.