This is a good explanation: https://stackoverflow.com/questions/46516395/whats-the-difference-between-hydrate-and-render-in-react-16#46516869 https://stackoverf

This is a good explanation: https://stackoverflow.com/questions/46516395/whats-the-difference-between-hydrate-and-render-in-react-16#46516869 https://stackoverflow.com/questions/46516395/whats-the-diffe... TL;DR: It is used to attack event listeners to server rendered apps.