Advertising
This is how the big social platforms and Google make most of their money, selling attention. Advertisers pay per click or per impression, priced like an auction against everyone else who wants that audience at that moment.
- Simple to add using an existing network like Google AdSense. No cost to your users.
- Only pays real money at scale: tens of thousands of engaged, returning users. Ads annoy people, so it's usually better to hold off adding them until you have that scale.
