sat nav info

[greendog]

Can anyone help me find out more about satellite navigation databases?
What I mean is, I want to know how the information for points of interest is collected and where it is stored e.g. if I go to my sat nav and search for a restaurant and it comes up with 'The Blue Lagoon Chinese Restaurant', then where did that information come from, where is it stored and how do you contact the people who compile this information?
Thanks.