Hypermodernism definition What are the features of hypermodernism? I know that one feature is controlling the center indirectly (f.ex. fianchetto), and letting the opponent control it with pawns. But I am not sure if there are other features. Nimzowitsch, who was the inventer of the hypermodernism style, wrote several new ideas in his book , such as overprotection, prophylaxis, rook on the seventh rank, knight outposts an so on. Are these ideas also considered as a part of the hypermodern style or is there a clear definition on this?
It seems to me you have the idea spot on already. Traditionally, chess theory was that the best way to control the center was to occupy it. Some players (like Nimzowitsch and others) showed that this was not necessarily true and that there is merit in letting your opponent occupy it while you undermine it from a distance.

I'm not sure if the idea was really novel at the time, but it became popular and as we do whenever we see a pattern we have to name it.

Beyond that I doubt there is much to learn from "hypermodernism" (which is not to say that there is not much to learn from the various rich and deep ideas behind each of the so labelled openings themselves).