Okay, now that you know how to use several different tags, I need to tell you about nesting. Nesting means that when you put several pairs of tags into a document, you must balance each pair of tags, making sure they do not overlap. It is easiest to understand with an example. So here is an example using the emphasis or italics tags, <em></em>, and the strong or bold tags, <strong></strong>:
If you have overlapping tags, then your document will be displayed by the web browser in ways you didn't expect.
Let me give you a more complicated example because this nesting thing is really important. Trust me, it can cause you some major problems later on when you start filling up your document with a whole lot of tags…
As you can see in the second example, you need to put </tag 3> before you put </tag 2>.
This resource originally created by Deborah Dunk.