Checkbox

A single flag: on or off.

Settings: the label shown beside the box, the default state, width.

The value is cast to a boolean on save, so the template reads it directly:

{if $is_featured}
    <span class="star"></span>
{/if}

"Required" is hidden for this type on purpose

An unticked box has a value — false — so there is nothing for a required check to catch. When the answer genuinely has to be given rather than defaulted, use List Yes/No: an empty dropdown is visibly unanswered, an unticked box is not.