Text may even include a certain limited subset of HTML (don't worry, the subset is chosen to be safe from cross-site scripting attacks). This is useful for creating links:

You might want to link to <a href="http://jboss.com/products/seam">something
cool</a>, or even include an image: <img src="/logo.jpg"/>

And for creating tables:

<table>
    <tr><td>First name:</td><td>Gavin</td></tr>
    <tr><td>Last name:</td><td>King</td></tr>
</table>

But you can do much more if you want!