In three-dimensional space, a coordinate must be given in terms of three independent variables. In the context of geocaching, where it is usually assumed that the geocache is sufficiently close to the earth's surface, only two variables are needed, often referred to as latitude and longitude.
Each designation of a coordinate can be given in terms of some unit system. In most cases within geocaching, the latitude and longitude are written in degrees and minutes. On geocaching.com, the most common format used is ddd° mm.mmm'.
Several differing data are used in designating coordinates, based on geographical surveys. The most frequently used datum set is WGS84 as it tends to be the most recent survey.