I tried this from a couple of computers, so I think it must be part of the page.
It’s a news item, and when I tried to cut and paste a short phrase from the story into my search engine, the clipboard contained my selection plus a link to that page.
Here’s the page I’m looking at
I highlight the words “UCLA study showing a link between soda and obesity” and hit Ctrl-c
It appears the page is using a bit of JavaScript magic to append that text whenever you copy from it (but maybe only for long enough chunks of text). You can turn off JavaScript if you’d like.
It does appear that they take action on highlight, not on actual cut and paste. I would submit that there’s a very large percentage that isn’t even THAT meaningful. To quote from that discussion:
In my case, it’s not even necessarily the text I’m reading. If my hand happens to be resting on the mouse I’m often aimlessly highlighting stuff with it for no good reason at all - I’m just frobbing with the mouse. Any data they’re collecting on that is pretty much garbage.
I habitually highlight next near where I’m reading, so I can’t read the New York Times without disabling scripting or getting pop-ups with failed searches for giant terms.