The roads and its surroundings changes everyday. New road are opened, existing roads are changed and points of interest mushroom almost everyday. Map producers spend a huge amount of resources to ensure that their maps are up-to-date. Each of these updates are released for the Users to update their maps in their Personal Navigation Device (or GPS). Map updates are not downloaded via the GPS signals during use. When the new maps updates are released and you can download it using and internet connection and a computer. the map is then placed in the memory of the device. Once done, you can use your GPS without the need of an internet connection. Making the map resident in your device also significantly improves navigational function and performance. This mode is applicable to ALL GPS and Navigation devices and applications including Garmin Mobile XT.
P.S. Some maps are free some are not. Garmin map updates are approx USD99 each. This annuity revenue is the business model of map producers.
However, Google map/navigation stores their map in their central DB and when you use it, you utilize your internet connection to download the map of your locale into your temporary memory. So every time you use it, you are accessing the latest map. On the downside, this approach will also delete the map every time you stop Googlemap. You need to have internet connection active during the entire time you are using Googlemaps thus incurring charges. The performance of your internet connection also impacts the performance of Googlemap.
