Historically, gazetteers served as indexes to place names on map sheets or maps in atlases. A person could look up a place name in the gazetteer and get a page or map sheet number along with a grid reference (e.g., E4) and be able to find it on a map. The gazetteer thus served an important role in information retrieval. In its digital incarnation, a gazetteer serves a similar role as an aid for information retrieval.

One of the most widely used and known gazetteers in the United States is the Geographic Names Information System (GNIS). This digital gazetteer is maintained by the U.S. Geological Survey along with the U.S. Board on Geographic Names. As of December 21, 2009, there were 2,123,538 entries in GNIS covering ...