what`s the two tags in the AndroidMenifest.xml used for
<p>in the hello world project of android, there are some code in AndroidMenifest.xml that i am not really know what they used for.what`s the difference between action and category element.
thanks in advance.</p>

<pre><code>&lt;activity android:name=".HelloWorld"
android:label="@string/app_name"&gt;
&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;
&lt;/activity&gt;
</code></pre>
