title: What is the meaning of android.intent.action.MAIN?
body: <p>I have seen so many different confusing explenations..</p>
  
  <pre><code>&lt;intent-filter&gt;
       &lt;action android:name="android.intent.action.MAIN" /&gt; 
       &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
  &lt;/intent-filter&gt;
  </code></pre>
  
  <p>What is the meaning of</p>
  
  <pre><code>&lt;action android:name="android.intent.action.MAIN" /&gt;
  </code></pre>
  
  <p>and</p>
  
  <pre><code> &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
  </code></pre>
  
  <p>and</p>
  
  <pre><code> &lt;category android:name="android.intent.category.DEFAULT" /&gt;
  </code></pre>