Twitter is shaking up its central formula, i.e. what its users see in their timelines.

Until this week, your Twitter timeline was pretty predictable in that it only contained tweets from accounts you follow. This category, of course, includes original tweets from individuals you don't follow but that were retweeted by someone that you do.

That's all changing. Early this week, outrage erupted on Twitter (how meta) when some users noticed that tweets they'd merely favorited were showing up in their followers timelines as if they were retweets.

Related: Chill, People. Why You Shouldn't Hate Twitter For Adding Favorites to Timelines.

While, as we pointed out, favorited tweets were never private, the general complaint was that by treating favorited tweets like retweets, Twitter was cluttering users' timelines with unwanted content.

Or more succinctly, in the words of @xmaario:

If you didn't like this change, there was still hope that it was just a temporary pilot run and that Twitter would concede to all its pissed off users and return to treating favorites like favorites and retweets like retweets.

You can stop holding your breath. It's now officially official: Twitter has expanded the types of tweets it includes in your timeline, not just to encompass tweets favorited by accounts you follow, but also tweets, accounts and "other content" it deems "popular or relevant" to you.

Related: 10 Tips for Mastering Twitter

Here's the official new policy, courtesy of Twitter's help document "What's a Twitter timeline?"

Additionally, when we identify a Tweet, an account to follow, or other content that’s popular or relevant, we may add it to your timeline. This means you will sometimes see Tweets from accounts you don’t follow. We select each Tweet using a variety of signals, including how popular it is and how people in your network are interacting with it. Our goal is to make your home timeline even more relevant and interesting.

As many have pointed out, this change effects how Twitter functions on a pretty basic level. Presumably your Twitter timeline will start to look more like your Facebook newsfeed; instead of being a chronological list of tweets from accounts you follow, it will become more of a curated list showcasing content that Twitter thinks will interest you.

Depending on how you look at it, this move either "pollutes" the user experience, or it improves it by surfacing relevant content. No matter your position, however, one thing is certain: Twitter now has a lot more influence over what goes in your timeline.

Related: Why I Follow 15,000 People on Twitter