Online Business idea?

[Jake]

Some ad networks like Google's Adsense matches ads to the text content of each page, or in some cases when an ad doesn't seem to match the content the space may be offered on a banner ad trading desk where in some case re-targeting ads are tailored to the current viewer of a page, based on their prior internet history, ecommerce sties that appear to be stalking someone has set a cookie in the visitor's browser which is used to trigger these re-targeting ads.

There are ad space broker sites like buyads.com, buysellads.com and blogads.com that assist you in doing direct banner space sales, in these case you have approval rights for each ad shown, so you can be sure they are relevant and suitable for your visitors. You typically need thousands of visitors a week to qualify for these ad brokers.