<kbd>
A key, a gesture or a command typed by the person using it.
Nesting carries meaning. <kbd><kbd>Ctrl</kbd>+<kbd>C</kbd></kbd> marks a combination made of individual keys, not a key called "Ctrl+C". Inside <samp>, it indicates input echoed back by the system.
The browser default is merely monospace. The key-cap drawing everyone expects is CSS.
<p>
To find a specimen, press
<kbd><kbd>Ctrl</kbd> + <kbd>F</kbd></kbd>.
</p>