An introduction to the principles of unified georeferencing, which uses placename and geospatial referencing interchangeably across all types of information storage and retrieval systems. Georeferencing--relating information to geographic location--has been incorporated into today's information systems in various ways. We use online services to map our route from one place to another; science, business, and government increasingly use geographic information systems (GIS) to hold and analyze data. Most georeferenced information searches using today's information systems are done by text query. But text searches for placenames fall short--when, for example, a place is known by several names (or by none). In addition, text searches don't cover all sources of geographic data; maps are traditionally accessed only through special indexes, filing systems, and agency contacts; data from remote sensing images or aerial photography is indexed by geospatial location (mathematical coordinates such as longitude and latitude). In this book, Linda Hill describes the advantages of integrating placename-based and geospatial referencing, introducing an approach to "unified georeferencing" that uses placename and geospatial referencing interchangeably across all types of information storage and retrieval systems. After a brief overview of relevant material from cognitive psychology on how humans perceive and respond to geographic space, Hill introduces the reader to basic information about geospatial information objects, concepts of geospatial referencing, the role of gazetteer data, the ways in which geospatial referencing has been included in metadata structures, and methods for the implementation of geographic information retrieval (GIR). Georeferencing will be a valuable reference for librarians, archivists, scientific data managers, information managers, designers of online services, and any information professional who deals with place-based information.