PC Pro UK has a fascinating article about the navigational maps we use on our devices and how they are made. This behind-the-scenes look examines how the four biggest digital map providers maintain their vast repository of information.
Nokia-owned Navteq has a database that includes 24 million miles of roads and makes 2.4 million changes to its database each day, says Navteq's vice president Frank Pauli. These changes are made based on information provided by users, governments and its own mapping efforts.
Another big map provider is Dutch company TomTom. TomTom is not as big as Navteq, but it is able to effectively use data supplied by its devices which phone home with information. It also has an active base of users who send in 15 million map changes each year.
There's also Google which PC Pro describes as having a "mishmash" of maps, some of which are licensed and some of which are generated in-house. Lastly is the OpenStreetMap project which started off small and has emerged as a major player in the recent years. OpenStreetMap relies almost entirely on user-based submissions that can modify a map within minutes.
You can read more about each of these solutions in the PC Pro UK article.