More and more search engine users are expecting direct answers to their information needs, rather than links to documents. Semantic search and its recent applications enabled search engines to organize their wealth of information around entities. Entity linking and retrieval provide the building stones for organizing the web of entities. This tutorial aims to cover all facets of semantic search from a unified point of view and connect real-world applications with results from scientific publications. We provide a comprehensive overview of entity linking and retrieval in the context of semantic search and thoroughly explore techniques for query understanding, entity-based retrieval and ranking on unstructured text, structured knowledge repositories, and a mixture of these. We point out the connections between published approaches and applications, and provide hands-on examples on real-world use cases and datasets.