I was watching a Pluralsight course on React and the instructor stated that props should not be changed. I'm now reading an article (uberVU/react-guide) on props vs. state and it says

  
Both props and state changes trigger a render update.

Later in the article it says:

  
Props (short for properties) are a Component's configuration, its options if you may. They are received from above and immutable.

• So props can change but they should be immutable?
• When should you use props and when should you use state?
• If you have data that a React component needs, should it be passed through props or setup in the React component via getInitialState?