They are rings of STEEM accounts that are often automated to post (usually plagiarized) content every few minutes or hours with the idea that Steemit can be used to generate no or low-effort passive income by doing so. They generally upvote each other as well. The tactic doesn't actually work well to make money because people can tell the accounts are fraudulent and rarely reward them. Moreover, when they are discovered they will get put on blacklists and their meagre rewards reduced to zero.

You may already know this, but the term "faucet" comes from sites like http://moonbit.co.in/ that offer users a steady but very tiny trickle of satoshis for clicking a button (surrounded by many advertisements.) The basic idea is "free money" but as we know "there's no such thing as a free lunch!"

@daan