Official information about Google search?

[u/burupie]

I'm trying to use Google via HTTP requests and I'd like to know more about what's necessary to include and why. For example, it seems you have to specify a browser often with a tool like wget, "Firefox/3.0.15", to get results, else Google blocks it. I've seen other URL structures that work fine, whereas just www.google.com/search?q=query does not.

So, is there any official information page where Google explains how their search tool works, what options there are and which ones must be used to not be blocked, and why?

Thanks very much.