title: Meaning of \d{1-3 }in regular expression
body: <p>I've been searching for a long time but didn't find an answer for my question, can tell me what the meaning of</p>
  
  <pre><code>(?:[-\w\d{1-3}]+\.)+
  </code></pre>
  
  <p>and not </p>
  
  <pre><code>(?:[-\w\d{1,3}]+\.)+
  </code></pre>
  
  <p>I don't understand the {1-3} part and can't find anywhere what it's mean.
  Thank you</p>