A citation is a brief notation describing a source of information or quoted passage. The purpose of a citation is to acknowledge or give credit to the source and identify its location. A citation typically includes the source title, author, publisher, date and place of publication.The exact format and content of a citation may vary from one discipline or field to another, depending on the style guide used for a particular field. The Chicago Manual of Style is a good, general style guide, often used in the social sciences, which includes genealogy.
In genealogy, citations are used when documenting sources. A good citation allows others to verify the accuracy of information and can lead others to a source that may have additional information relevant to their research. Good citations are the hallmark of a good researcher. A popular reference for citing sources in genealogy is Evidence: Citation & Analysis for the Family Historian by Elizabeth Shown Mills.