How Android apps get notifications even without being launched?
<p>Consider the apps that large blogs have (which work pretty much like an RSS feed but for your phone). Whenever the blog publishes a new post the app creates a notification on the user's phone about the new post.</p>

<p>Here's are some things I would like to understand about those:</p>

<ol>
<li>Is that notification being pulled by the app on my phone or being pushed to it by the blog?</li>
<li>How come this works even if I have not launched the app?</li>
<li>What classes and services of the Android platform are used to create such apps?</li>
</ol>

<p>Thanks a lot.</p>
