If you need a bit of a reminder, Facebook's Live Video feature is essentially a way for users of the social network to broadcast live video from their phones. There's no need to download a separate app like Periscope or Meerkat; the feature is baked right into the main Facebook app itself. Similarly, users of the social network can watch those video streams right on their Facebook feeds.
We've ragged on Facebook's algorithm before for prioritizing certain content over others, but surfacing live video when it's actually live makes a lot of sense. In a blog post, Vibhi Kant and Jie Xu wrote: "People spend more than 3x more time watching a Facebook Live video on average compared to a video that's no longer live. This is because Facebook Live videos are more interesting in the moment than after the fact."
As for when you'll see them, live streams should appear at the top of your feed starting today. Don't forget to react appropriately when you do.