decimal degrees: Information and Much More from Answers.com

Decimal degrees (dd) are often used in Geographic Information Systems (GIS), web-mapping applications such as Google Maps, and GPS devices to express latitude and longitude coordinates, rather than expressing geographic coordinates with degrees, minutes, and seconds (dms).

For example, with DMS, the geographic coordinates of the United States Capitol are "38° 53' 23" N, 77° 00' 32" W". In decimal degrees, West and South are considered to be negative numbers and the DMS is converted to degrees using the formula (D + M/60 + S/3600). Thus the decimal degree representation of the U.S. capitol is "38.8898341, -77.0088651".