Very newbie question.
For instance, is this okay?
<a href="allaboutpeanuts.html">Peanuts<img src="peanut.jpg"> </a>
I tried it and it works fine, but I've been googling around and I can't find any mention of anyone putting more than one element in an a href. So are you not actually supposed to do that, but I cheated, so it's sort of a hack?
Yes, it's correct - you can place one element into another. The only illegal thing is to place block elements inside inline elements.
Yes, absolutely. HTML tags can be nested in any combination and any number.
The main rule is that they must nest properly. So this is not valid:
<a href="allaboutpeanuts.html">Peanuts <h1>Lovely <img src="peanut.png" alt="Peanut" /></a> Peanuts</h1>
The h1 tag is not completely inside the a tag.
This, however, is entirely valid:
<div><h1><a href="allaboutpeanuts.html">Peanuts <img src="peanut.png" alt="Peanut" /></a></h1></div>
This is perfectly valid HTML, just note the following constraints:
In HTML 4.01 and XHTML, only inline elements are valid as children of an <a> tag (e.g. <span>)
In HTML5, this has been changed to allow non-interactive block level elements - e.g. you can nest <p>, <div>, <h1> or even <section>, but not a further <a> or <input>. [See The a element]