const [state,setState] : Return of useState, the arguments allow reading and updating of the state associated with the hook instance.
state : Current state.
setState: Current status updater.
useState( optionalInitialState ): Function that associates the state to the webcomponent:
optionalInitialState: Optional parameter that defines the initial state associated to the hook instance, If optionalInitialState is a function it will be executed in order to obtain the initial state only at the moment of the hook instance for the first time.