title: HTTP Header "X-NewRelic-ID"... What is it?
body: <p>I am seeing some requests coming through one of my sites that have the <code>X-NewRelic-ID</code> request header attached. It's always in the form of a header.</p>
  
  <p>Does this identify a user or simply a unique request passing through one of their services?</p>
  
  <p>Thanks</p>