To tell the elements how to respond to, say, the click of a button, we need a way of interacting with them.

The first step in doing that is giving each element an ID.

<html>
<body>
<h3>Tweeter</h3>
<p>
<em>What's up?</em>
</p>
<p>New Messages</p>
</body>
</html>]]>