Although GPS technology has been around for a long time it has only been in the last years with advanced technology that it became so pervasive. Most likely you have used GPS in a car or maybe even in a handheld device. GPS technology is so small and cheap today that it is now embedded in more and more devices and cameras are not an exception anymore.

But first some background about what GPS is and how it started. GPS stands for Global Positioning System. It started as a military system that the US army deployed in order to allow it to accurately read the position of each of its vehicles anywhere around the world. The GPS system was later on opened for civil use but for many years the US army limited the civil GPS accuracy to a few tens or hundreds of feet which significantly limited its usage. In the last years though the GPS system was opened up and today civil GPS receivers can pinpoint their location in very high accuracy of a few centimeters.

The GPS is a system of satellites that orbit earth at a known height and location. The GPS system is very simple in concept. A GPS receiver picks up the signal from a few satellites. The satellites encode some information such as their id and clock. The GPS receiver calculates the exact location of each satellite it is receiving signal from and then triangulates in order to get a perfect reading of its location.

As civil GPS accuracy improved and as its usage increased its price dropped significantly. With advanced microelectronic technology GPS receivers are ever smaller consume less battery and cheaper. In its early days GPS receivers were big and could only fit in cars and other bigger vehicles. Today it is possible to embed a GPS receiver in small electronic devices such as cellular phones wristwatches and digital cameras.

Embedding a GPS in a digital camera provides what is known as geo tagging. Long ago cameras offered timestamp tagging of photos. If the digital camera clock is set to accurate time then each photo taken includes a small print of the time it was taken on the bottom right corner. With digital cameras timestamp is no longer actually printed on the photo but instead it is included as part of the digital photo file meta data.

Geo tagging is very similar to timestamp tagging but instead of logging the time when the digital photo was taken with geo tagging the digital camera logs the exact geo location where the photo was taken. This information is stored as part of the digital photo file meta data. As most digital cameras support the EXIF format geo tagging is stored as a field in the EXIF record for each digital camera.

Geo tagging information is later on used by digital photo viewers. Photo viewers that support geo tagging can read the location information and then correlate it with a map to show where the digital photo was taken. No more are there photos that were taken long time ago and you cannot remember where they were taken and when. With geo tagging there is no more need to guess or to write down that information as it is stored perpetually alongside with the digital photo in an accurate format.