This content/posting/article is partially reproduced from TripTracker.net , source: http://triptracker.net/faq/

1. Q: What is a GPS track and how do I create one?
   A GPS track is a file which contains information about the geographical location of places that you have visited while traveling with the GPS receiver. Essentially, a GPS track could be exported from your GPS receiver / data logger in GPX, NMEA or KML format.
   
   You can transfer that information from your GPS receiver to a computer, Geotagged (see tutorial in our forum), upload to to any Web Album such as Google Picasa, Flickr, Locr, or TripTracker.
   
   Any photo that has been geotagged will be displayed with travel path on satellite imagery of the places where you have traveled.
   
   Usually a GPS track file contains points with information such as the longitude, latitude and altitude of the point and the time at which you visited that point.
   
   Geotagging software uses this information to set the exact location of your journal entries and each photo you have taken on your trip and thus visualize the trip on the map.
   
   Please learn more about Geotagging in our Geotagging Guide: Hardware, Software, and Workflow
   
   
   
2. Q: How does a Geotagged photo knows the geographical location where the photo was taken?
   By combining the time stamp embedded in each photo taken with a digital camera and the time information retrieved from the GPS track points, the location where the photo was taken can be determined quite accurately.
   
   However, there is a catch. The time embedded in each photo is dependent on the time setting on your digital photo camera.
   
   Thus, make sure that the local time is accurately set on your digital camera before you begin taking pictures. Note that after you have changed the time information of each photo, the location information is automatically readjusted to reflect the change of time.
   
   
   
3. Q: How do I view the time embedded in the photo?
   Embedded time is stored in an EXIF header of each JPG photo under the "Date picture taken" property. If you are using Windows, you can see the EXIF information from Windows Explorer by right-clicking on a photo file and selecting "Properties" from the menu. In the "Properties" window, select the "Summary" tab and click "Advanced". There you will be able to view the time and date the picture was taken, as well as other information about the photo.
   
   For Example:
   
   
   
   
4. Q: What should I do if my trip spans over different time zones?
   When crossing a time zone border always try to remember to update the time on your digital photo camera. Only in this way can we assume to have an accurate local time embedded in the photos.