Content model: Transparent, but there must be no interactive content descendant.

The a element may be wrapped around entire paragraphs, lists, tables, and so forth, even entire sections, so long as there is no interactive content within (e.g. buttons or other links).

In other words, you can nest any elements inside an <a> except the following:

<a>

<audio> (if the controls attribute is present)

<button>

<details>

<embed>

<iframe>

<img> (if the usemap attribute is present)

<input> (if the type attribute is not in the hidden state)

<keygen>

<label>

<menu> (if the type attribute is in the toolbar state)

<object> (if the usemap attribute is present)

<select>

<textarea>

<video> (if the controls attribute is present)