<fieldset>
Groups related controls, with legend as the group's caption.
Baseline: Widely available · Forms
When to use it
Mandatory for radio and checkbox groups — the legend is announced with each control's label; disabled on it disables the whole group.
When not to
Don't use it as a generic bordered box; it announces itself as a group.
Key attributes
disabled- disables all contained controls
name / form
Example
<fieldset>
<legend>Preferred edition</legend>
<input type='radio' id='ed-text' name='edition' checked>
<label for='ed-text'>Plain text</label>
<input type='radio' id='ed-html' name='edition'>
<label for='ed-html'>Semantic HTML</label>
</fieldset>