title: Universal Analytics clientId vs userId
body: <p>The docs describe the clientId as: </p>
  
  <blockquote>
    <p>This anonymously identifies a particular user, device, or browser instance.
    <a href="https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#cid" rel="noreferrer">https://developers.google.com/analytics/devguides/collection/protocol/v1/parameters#cid</a></p>
  </blockquote>
  
  <p>It can be used to send server side hits to analytics while still tying them to a particular user.</p>
  
  <p>There is also a feature in closed beta called userId, which you will be able to pass once a user has authenticated: <a href="https://developers.google.com/analytics/devguides/collection/analyticsjs/user-id" rel="noreferrer">https://developers.google.com/analytics/devguides/collection/analyticsjs/user-id</a></p>
  
  <p>userId is fairly self-explanatory.  However, UA also allows you to pass your own clientid if you choose to.  For developing CRM type tools, can one just associate the clientid with a user in the same way that you would with a userid?  The goal is primarily to be able to track offline interactions and connect them with visitors in Analytics.</p>