The digital acquisition of information – known as Information Retrieval – has gained enormous importance in recent decades. Due to modern technologies and the spread of multimedia content, the focus is shifting more and more toward Multimedia Information Retrieval (MMIR). This well-founded and comprehensive textbook conveys the fundamentals and formal concepts of MMIR and connects them in a practical way with current developments from research and technology. Both the classical models of MMIR and modern, AI-based methods are presented. The book is aimed at computer science students as well as teachers and professionals in the field of software development who deal with topics such as multimedia, information processing, or user interaction.The ContentInformation and knowledgeFeatures and feature representationInformation RetrievalEnterprise concepts of Information RetrievalEvaluation and relevance metricsApplications and outlook