- Components can render other components. This makes React very extensible and compositional. Oftentimes you'll be to find components for common web tasks that have already been developed and are available via `npm`. You can bring those components into your application so you don't need to rewrite components for those common tasks again.
- CSS. Should this live in the hello world or another resource?
- JSX. Same question.
  - Note you can use React without JSX (`React.createElement`) though it isn't super common.



- Data validation using propTypes
- Forms
- Events
- router?
- Axios for APIs
- testing in react?
- firebase?
- setstate happens asynchronously!!!

 - install chrome debugging plugin


- make lifecycle methods conversation much more compelling
