You may purchase street map packs as downloads, or as SD card updates.I actually prefer SD card updates for their simplicity and ease of use.Drivers on all the major roads of Europe, people at computers assembling and adding changes - its a huge industry.Here at Landis Media, we employ 5 people just to update the location and POI information which we supply. However - maps are so much more complicated than locations.But for many map options, especially international street maps beyond those you purchased with your unit, you will have to pay.If you've purchased one of Garmin's many GPS units that offer free map updates, you will choose this map updates page, which will prompt you to download and install the Garmin Express map updater utility, if you don't already have it installed.The Garmin Express application is key to updating maps for many devices.Garmin Express lets you update your maps, upload activities to Garmin Connect, update your golf course maps, and register your products.
Express should automatically find your device and show that it is connected.
Aviation is a separate and highly regulated part of Garmin's database offerings.
The Fly Garmin site serves as your central resource for staying on top of the latest information and keeping your data current.
Creating and updating maps takes a lot of people and an awful lot of time !
There are just two major map suppliers - Tele Atlas and Navteq and they have massive teams of people working on this.