Subtitle
In a library context, a subtitle is a secondary title or phrase that appears below the main title of a book or other publication, and that provides additional information about the content or focus of the work. Subtitles are often used to clarify or expand on the main title, or to indicate the subject matter or scope of the work. For example, a book with the main title “The History of Rome” might have the subtitle “From the Founding of the City to the Fall of the Western Empire.” Subtitles are often included in library catalogs and databases, along with the main title and other bibliographic information, to help users understand the content and focus of the work.