Using the Right Tag for the Right Job - HTML5 Mastery: Semantics, Standards, and Styling - page 64

Although description lists are flexible in use, you should bear the following caveat
in mind: a definition term can only contain phrasing content, not flow content, so no
paragraphs, headers, or lists—which means that terms cannot be given differing levels
of importance in the same way that headings can ( h1 , h2 , and so on). A description ele-
ment ( dd ) in the list, however, can contain any flow element or series of elements, so
long as they're well-formed.

Diagrams, photos, illustrations: figure and figcaption

The idea behind the figure element is to provide diagrams, images, code, and so on,
optionally with a caption or legend ( figcaption element) as a self-contained unit that
is relevant to the main content of the document. The figure should be able to be moved
or removed without destroying the overall layout of the document.
For example, the following shows two images side by side, with a caption below (see
Figure 2-6 ) :
<figure>

<img src="earth.jpg" title="View of Earth"

alt="Photograph of the Earth from space.">
<img

src="mars.jpg" title="View of Mars"

alt="Photograph of Mars from space.">
<figcaption>The Earth and Mars shown side-by-
side.</figcaption>
</figure>