There are multiple ways to make revenue off a website without selling a product or service.
Aside from affiliate programs, there's also advertisements (this is the most common method), however keep in mind that these sites don't automatically make you money. You need a decent amount of visitors to make $ off a site. And don't expect to make a $100 a day without any work. Also the amount of money you make depends on various factors, #1 your visitors, where are they from, are they actually interested in the content in your site etc. #2 the niche of your site, advertisements for certain niches pay higher than others. And there are a couple of other factors, I just named the most important in my opinion.
