Datum - The units of latitude and longitude, each datum describes the shape of the Earth differently. Most GPS units use the datum WGS-84, while older maps in the US use NAD27.
ESRI Shape File - File format for ESRI GIS software, such as ArcView.
GIS - Geographical Information Systems. Software that deals with locations on the earth.
Geo-referenced Photos - Photos with the latitude / longitude of where they were taken.
JPG or JPEG - File format for storing digital photos.
Memory Card Reader - A device that connects to a PC that accepts compact flash or other types of digital camera memory devices.
NAD 27 - North American Datum 1927. Latitude and Longitude unit, used on some older maps.
NMEA - National Marine Electronics Association standard for communicating with GPS receivers.
Time Stamp - Date and time information, either in the Track Log or the photo.
Track Logs - Location points saved in the GPS Receiver's internal memory.
User Data - User comments or data entered on a scripting digital enabled camera.
Watermark - Text written onto an image, such as the date and time.
WGS 84 - World Geodetic System 1984. Datum used by most GPS receivers and newer maps.