don't use inheritance, only use composition and props!!!
ch.12
Thinking in React: 1. component hierarchy; 2. build a static version in React(you can use props but no state); 3. minimal state; 4. lifting state up; 5. inverse data flow
After the first round reading of the tutorial https://reactjs.org/docs/hello-world.html, IMO the most important concepts in React are: Components, Props, and State.
