Think it's been answered, but the link below might provide more information on tracking pixels/beacons.

https://en.wikipedia.org/wiki/Web_beacon

Thanks for that, I've seen/heard of tracking pixels but haven't tried them yet.

I think this reflects writing software in some ways, judicious 'editing' is important. It's realizing what you don't need that is as important as what you do need to keep in there, at least in terms of avoiding snowballing tech debt/feature creep.

My first attempts at writing were monstrosities of flowery descriptions and long-winded dialogues, an awful hybrid prose/poetry. That didn't improve, but I realized the art is getting an interesting message across as simply as possible, not showing off your vocab or pre-empting the reader's imagination.