A unique identifier (like a street address) given to library items so they can be easily found. Items about the same subject often have similar call numbers. Major call number systems include Dewey Decimal and Library of Congress.

A type of database, searchable online, used by libraries that includes information about the items they own or subscribe to. Each item’s record in the catalog provides information like title, author, call number, and floor location.

A source that has been recently published, generally in the last 5 years. Different disciplines use various year ranges to determine what is current.
An evaluation criteria used to determine if the date of publication of the information is suitable for your paper, speech, presentation, project, etc