Nearly everything that you do on a page is trackable if you have JS enabled including how you moved your mouse on the page (https://api.jquery.com/mousemove/).
To keep the technical details short: the events are logged with JS and sent over either ajax or a websocket in the background as you navigate the site.
To keep the technical details short: the events are logged with JS and sent over either ajax or a websocket in the background as you navigate the site.