Some interviews are biographical, that is, about an individual's own life.
Others concern the narrator's knowledge about a specific topic or event and are often limited to very short time span. The practice of telling a story, rather than writing it has, of course, been around for thousands of years. Oral history, as a discipline, has only been in existence since the late 1940s and the development of the tape recorder. Oral history collections are often overlooked in genealogical research. However, a researcher might find an oral history interview with a relative that could give fascinating and important details about that person's life and activities.