EDIT: "license under any Necessary Claims" seems to mean a license to the patents necessary for React as pointed out by https://news.ycombinator.com/item?id=150

EDIT: "license under any Necessary Claims" seems to mean a license to the patents necessary for React as pointed out by https://news.ycombinator.com/item?id=15052962 https://news.ycombinator.com/item?id=15052962 >> A "Necessary Claim" is a claim of a patent owned by Facebook that is necessarily infringed by the Software standing alone.