State

The state contains component specific data that may change over time and allows components to respond to user input or network responses by changing their outputs. Similarly to props, changes in the state will cause re-rendering of the component. State and props differ, however, in the way that the state is fully controlled by its respective component.

Note that in the listed documentation over, class components are used, e.g. in the ticking clock example, when adding a state to the component. This is, however, not necessary anymore due to the Hooks update. We will explore the Hook concept in the next section.