The best kind of ads are the ones that don’t even seem like ads. These are known as native ads, where the advertisement is practically indistinguishable from the content around it, which is especially easy on a website like Tumblr where of the content is visual and quickly absorbed. The introduction of ads on Tumblr have been the only noticeable difference in the service since Yahoo acquired it back in 2013, however, that level of independence may finally be coming to an end as Yahoo seeks to turn Tumbr into a more profitable service.