title: What does authSource means in mongo database url?
body: <p>i am trying to connect to my mongo database with following connection string</p>
  
  <pre><code>var Mongo_url = 'mongodb://MyUSer:tech@localhost:27017/chatme?authSource=admin';  
  </code></pre>
  
  <p>I am getting error as </p>
  
  <pre><code> assertionError: null == { [MongoError: Authentication failed.]
   name: 'MongoError',
   message: 'Authentication failed.',
   ok: 0,
   code: 18,
  </code></pre>
  
  <p>Could anyone please clear this "authSource=admin" thing to me.</p>