Defines a group of option elements in a select form field.
The optgroup element is used to group option elements in a select element.
<select>
<option selected="selected" value="none">None</option>
<optgroup label="Fruits">
<option value="Apple">Apple</option>
<option value="Pear">Pear</option>
<option value="Peach">Peach</option>
</optgroup>
<optgroup label="Vegetables">
<option value="Bean">Bean</option>
<option value="Cole">Cole</option>
</optgroup>
</select>