Two of the most under-used HTML tags are the fieldset and label tags. Never heard of them? I'm not surprised. Rarely will you find these tags on websites you visit. They certainly aren't anything spectacular, but in some cases your site can benefit from using them. Here is an example

The fieldset tag wraps elements contained within it, with a box - effectively grouping the items it wraps into a logical group. The fieldset tag can help you distinguish elements of your webpage from other elements of it. If you place a legend tag within the fieldset, you will also add a heading to the fieldset. You can see this in the example linked to above. The fieldset HTML is very similar in appearance to the GroupBox control used in WinForms development. Firefox renders the box with a squared appearance, while IE rounds its corners.

The other HTML tag that is rarely used is the label tag. The label tag is used to assign a label to other HTML controls on the page. Using the for attribute of the label control, you can bind the label to another control. Clicking the label, which is essentially text on the web page, will toggle the control it is bound to. This is especially useful for extending the clickable area of a radio button on your pages. You can see that too, in the example link listed above.

That's it! IMO, those are the two most under-used HTML tags on the web. I'm not sure how much they can help with SEO, or affiliate marketing, but they certainly could be used in more places across the web. 

Here's a look at the HTML in the example:

<fieldset>
<legend>Two Under Used HTML Tags</legend>
<input type="radio" name="tag" id="field" />
<label for="field">fieldSet</label>
<br />
<input type="radio" name="tag" id="lbl" />
<label for="lbl">label</label>
</fieldset>

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