It means it's an article paid for by a PR firm and subtly benefits one of their clients (while the topic of the article is true, or at least not an outright lie

It means it's an article paid for by a PR firm and subtly benefits one of their clients (while the topic of the article is true, or at least not an outright lie, and not obviously an ad). https://paulgraham.com/submarine.html https://paulgraham.com/submarine.html