title: When to use defer service provider?
body: <p>I read the laravel doc saying, </p>
  
  <blockquote>
    <p>If your provider is only registering bindings in the service
    container, you may choose to defer its registration until one of the
    registered bindings is actually needed.</p>
  </blockquote>
  
  <p>I don't understand what is "only registering bindings". I google and read many article, but I didn't find the answer.
  Could you help me to understand it!</p>
  
  <p>Thank you very much^^</p>