Twitter is pretty straightforward in that you only see tweets, retweets and promoted tweets from people you follow. Or at least that used to be the case.
As outlined in an updated Twitter Help Center page, the microblogging platform now has the ability to add content to your timeline from people you don't follow. The reasoning behind this decision is that you may otherwise miss content that's popular or relevant.
Such tweets are selected using a variety of signals including how popular it is and how people in your network are interacting with it. Twitter said their goal is to make your home timeline even more relevant and interesting.
Opinions on whether or not you think this is a good idea will likely vary. On one hand, you may discover new accounts to follow that you didn't even know existed thanks to the new feature.
Conversely, if you already have an active timeline filled with tweets from those you follow, this could make it even more crowded. Add to it the fact that many people simply don't want to see their feed filled with stuff they didn't ask for and Twitter could be facing some serious backlash.
As TNW points out, the initiative appears to have started a few weeks ago as a small experiment that has now rolled out to everyone.