title: REST APIs: custom HTTP headers vs URL parameters
body: <p>When do you use custom HTTP headers in the request part of a REST API ?</p>
  
  <p>Example: </p>
  
  <p>Would you ever use </p>
  
  <pre><code>GET /orders/view 
  (custom HTTP header) CLIENT_ID: 23
  </code></pre>
  
  <p>instead of</p>
  
  <pre><code>GET /orders/view/client_id/23 or 
  GET /orders/view/?client_id=23
  </code></pre>