If you're on other websites like YouTube, an online store, a random website, etc, yeah its based off of that.
That is true for most sites. However for sites like skyblock forums, this isn't necessarily the case. You may get ads on things you never seen before or searched before. Just as I stated in the intro, I got an ad of an 18+, which I never searched a game that was 18+ with n&&ds in it.