The classic HTML select dropdown list box has been with us for a long time, consisting of a container <select> tag which in turn contains a number of <option> tags which make up the list items which the user can then choose one from.
If you have a number of options which can be logically grouped, then there is a further tag that you can make use of, namely the <optgroup> tag. This allows you to group related options by placing them in the <optgroup> container, which coincidently has a non selectable label to make the various group definitions easy to see in the eventual drop down list.
In practice, your HTML would look like this:
<optgroup label="Swedish Cars">
<optgroup label="German Cars">
Which would translate to this on your web page:
Supported by all major browsers, it certainly is a useful little tag to keep in the back of your mind. If you want more information on the <optgroup> tag, why don’t you pay a visit here?