When to use radio buttons
Use radio buttons when a user can select only one item from multiple options.
When to not use radio buttons
Do not use radio buttons if the users should be able to select multiple options. In that case use checkboxes instead.
Example
<![CDATA[<fieldset class="form-item">
<legend>
<span class="fieldset-legend">Who will your audience be?</span>
</legend>
<div class="webform-element-description">Select only one.</div>
<div class="form-field-wrapper form-item js-form-type-radio">
<input id="faculty-checkbox" type="radio" name="audience" value="Faculty">
<label for="faculty-checkbox" class="option">Faculty</label>
</div>
<div class="form-field-wrapper form-item js-form-type-radio">
<input id="staff-checkbox" type="radio" name="audience" value="Staff">
<label for="staff-checkbox" class="option">Staff</label>
</div>
<div class="form-field-wrapper form-item js-form-type-radio">
<input id="students-checkbox" type="radio" name="audience" value="Students">
<label for="students-checkbox" class="option">Students</label>
</div>
</fieldset>]]>