Ctrl+C, or ⌘+C on Mac)Ctrl+V, or ⌘+V on Mac)The conversion is carried out by to-markdown,
a Markdown converter written in JavaScript and running locally in the browser.
Now conversion is done with Turndown, a HTML to Markdown converter written in JavaScript. The conversion is still done locally in the browser.
Thank you euangoddard, for creating this awesome copy/paste expereince: clipboard2markdown.