1. The name of the group is given by the first legend element that is a child of the fieldset element, if any
2. The remainder of the descendants form the group
3. The disabled attribute, when specified, causes all the form control descendants of the fieldset element, excluding those that are descendants of the fieldset element's first legend element child, if any, to be disabled
4. The form attribute is used to explicitly associate the fieldset element with its form owner
5. The name attribute represents the element's name

HTML

<form action="#">
    <fieldset>
        <legend>Do you agree?</legend>
        <input type="checkbox" id="chbx" name="agree" value="Yes!" />
        <label for="chbx">I agree</label>
    </fieldset>
</form>