Yeah, the React team takes backwards compatibility very seriously. They did finally drop some deprecated methods from the main package in React 16, but made th

Yeah, the React team takes backwards compatibility very seriously. They did finally drop some deprecated methods from the main package in React 16, but made them available as separate packages, and even wrote codemods to automatically replace usages. I can recommend several resources for understanding the changes in React 16: - Lin Clark's fantastic ReactConf presentation on "A Cartoon Intro to Fiber": https://youtu.be/ZCuYPiUIONs https://youtu.be/ZCuYPiUIONs - The official announcements for React 16: https://reactjs.org/blog/2017/09/26/react-v16.0.html https://reactjs.org/blog/2017/09/26/react-v16.0.html and https://code.facebook.com/posts/1716776591680069/react-16-a-look-inside-an-api-compatible-rewrite-of-our-frontend-ui-library/ https://code.facebook.com/posts/1716776591680069/react-16-a-... - A good summary of the major changes: https://www.infoq.com/news/2017/05/react-fiber-closer-look https://www.infoq.com/news/2017/05/react-fiber-closer-look - Two articles looking at the user-facing features and changes: http://www.benmvp.com/slides/2017/reactboston/fiber.html#/ http://www.benmvp.com/slides/2017/reactboston/fiber.html#/ and https://www.robinwieruch.de/what-is-new-in-react-16/ https://www.robinwieruch.de/what-is-new-in-react-16/