The GPS track log shows a complete history of your trip and enables the geotagging [wikipedia.org] of photos.
About the GPS track log
A typical GPS continuously records a series of track points (tracks) of where you have been.
About the track browser
PhotoLinker stores your complete track log history in a highly optimized database.
About GPX and TCX file formats
PhotoLinker uses GPX, TCX and NMEA formatted files to read the GPS track log.