Information retrieval (IR) is searching information resources satisfying specific information needs from within collections or data sets usually stored on computers. Mostly the information resources are text documents of unstructured nature. Whereas in the beginning information retrieval was a method only used by a restricted group of people such as librarians, professional searchers or people working in similar professions, today a lot of people engage in information retrieval, e.g. using search engines.
Moreover, information retrieval can be applied for browsing and filtering documents as well as for personal information retrieval applied on consumer operating systems.