In React, data flows in one direction only—from the parent to the child. This makes components really simple and predictable. They take props from the parent and render them. If a prop is changed at the top-level component, React will propagate that change all the way down the component tree and re-render all of the components that used that property.
Components can also have internal state, which should only be modified within the component. React components are inherently simple, and you can consider them as a function that take
state and outputs a virtual DOM representation.
In this chapter we look will look at:
props, short for “properties” ...