Switcher

For situations where you want to allow users to just enable or disable some options, you can consider the switcher field which allows only two values - true or false:

{
    "name": "lazyLoad",
    "label": "Lazyload",
    "group": "Additional",
    "note": "Enables lazyloading images that are currently not viewed, thus saving bandwidth.",
    "value": true,
    "type": "checkbox"
}

The switcher fields are great to handle conditional display of other options with use of the dependencies parameter described under Theme Settings API.