O que o registerServiceWorker faz no React JS?

Sou novato no React e queria saber qual é o objetivo de registerServiceWorker () no código a seguir?

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';
import registerServiceWorker from './registerServiceWorker';

ReactDOM.render(<App />, document.getElementById('root'));
registerServiceWorker();

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