Components have the ability to store data that can change over time.
When a component shows data that can change over time, we want changes to be shown as soon as possible. For example, consider the ProductList component: it shows a list of products contained in the products array. If a new product is added to the array, we want it to be shown immediately. React provides a mechanism to support the automatic rendering of a component when data changes. Such a mechanism is based on the concept of state.
React state is a property that represents data that changes over time. Every component supports the state property, but it should be used carefully.
Again, consider the ProductList component:
import React from 'react';
import Product from './Product';
class ProductList extends React.Component {
render() ...
