Bonus rollover confusing

I keep seeing these promos talking about "25x rollover" or "35x playthrough" and it just doesn't click for me how this actually works. I mostly play slots and sometimes dabble in live dealer, but most of the time I just stick with low-risk bets or pass if something seems tricky. For these bonuses, do they mean 25x the bonus itself, the deposit, or both? And does it matter if you’re playing slots or a live dealer game?

Half the time I can’t tell if I’m accidentally breaking some term and the bonus gets voided anyway. Anyone else just skip the promos altogether because the rollover rules are too convoluted? Is there a reliable way to track rollover progress, or do you have to keep your own notes?