title: What does the "single source of truth" mean?
body: <p>I have read <a href="https://reactjs.org/docs/forms.html" rel="noreferrer">this article</a>. In the "Controlled Components" part, there is a sentence: </p>
  
  <blockquote>
    <p>We can combine the two by making the React state be the “single source of truth”. </p>
  </blockquote>
  
  <p>What does the "single source of truth" mean?</p>