In the previous chapter, you looked into ways of finding texts that talk about particular concepts or facts. You’ve built an information-retrieval system that can search for texts answering particular questions. For example, if you were wondering what information science is or what methods information-retrieval systems use, you needed to provide your information-retrieval system with the queries like “What is information science?” or “What methods do information-retrieval systems use?” and the system found for you relevant texts that talk about these things.