What does authSource means in mongo database url? : <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>
