Where do foursquare or gowalla get their location data?

I k开发者_运维问答now foursquare uses google maps api, but how do they retrieve all the business locations from google maps? Do they save every location on their database or just access it when a user checks in? sorry if i have confused you, but im so curious!! :))

I did some research on this, what they do is they use the google maps api, to retrieve information for business locations, and geolocation, address, business etc, if someone deos check-in to a location, it gets saved into thier database. This prevents them from saving a lot of irrelevant locations.

Another thing is, users or businesses can create new locations if they wanted to, because not all location will be on the google maps!!

Hope that helps!