As our form grows larger and larger, we need to group them logically using fieldset and legend

<form>
  <fieldset>
    <legend>Billing Address</legend>
    <input type="text" />
    <input type="text" />
    <input type="text" />
    <legend>Payment</legend>
    <input type="text" />
    <input type="text" /> 
    <input type="text" />
  </fieldset>
</form>

Alternatively, you can replace with section and h2