If you type Google into Google, you will parse a URL

Jen: „I have it on good authority: If you type Google into Google, you can break the Internet.“
Alex at Github: „Yeah, well…“

To pick a zero point, let's choose the enter key on the keyboard hitting the bottom of its range. At this point, an electrical circuit specific to the enter key is closed (either directly or capacitively). This allows a small amount of current to flow into the logic circuitry of the keyboard, which scans the state of each key switch, debounces the electrical noise of the rapid intermittent closure of the switch, and converts it to a keycode integer, in this case 13.

Github: What happens when... (via Jason Kottke)