That depends: if you know the exact title, you would obviously use that. If you are searching for books about baseball—that would be an “authorized Library of Congress subject heading;” (use a subject search). However, if you are unsure of the exact subject or title, try a keyword search (for example, if “baseball” occurs somewhere in the title, or if it’s books about “baseball” and “business” that you want, try those as your two keywords—baseball AND business (Probably you would NOT use ‘baseball OR business’).

One advantage of searching by keyword is that, while it is much broader and less precise than a subject search, it does search for things like chapter headings in a table of contents, or other notes added to the record of a particular title—for example, sometimes poems listed in a collection or song titles on a CD can be located using a keyword search. When it is a song title or phrase you want, or a specific scripture verse, sometimes it helps to place it in quotation marks: “John 14:1”

The advantage of a subject search is that it provides an authorized set of headings and subheadings. For example, “Bible O.T. Joshua” as a subject search results in a list of Bible commentaries, interpretative and critical works, sermons on Joshua, etc.