How do applications acquire data in a non-manual fashion?

Hey everyone,

I'm wondering how do applications acquire a large data set. For example, if you have a website that contains all the cities around the world how do developers acquire that data? Sure in this example you can probably find an excel sheet somewhere on the net that has this information, but what about larger amounts of information like all the mountains in the world or in a specific area, or every single video game (phone/books/HDTV) that has been release and is expected to be released.

I know that there is a user approach such as a community of people enter this information down, but what if you don't have that community? There are also web REST api out there with some of that information but its pretty limited.

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Any advice/knowledge on this topic would be appreciated.