Unrelated, I'm sorry, but it sparked a memory from back in the days (1998-ish) when there was a banner-ad-system that cost no money, but it only advertised web

Unrelated, I'm sorry, but it sparked a memory from back in the days (1998-ish) when there was a banner-ad-system that cost no money, but it only advertised web sites, not products. Basically, it meant that you created a banner for your web site, somehow (I don't remember how) included in your web page, and the banner system would advertise your web site on other web sites using the same "technology", and vice versa. Thanks for triggering that memory! :)