You've probably heard some of your favorite YouTubers, artists, or other content creators promote their Patreon page. If you're not familiar with it, it's a site where you can give monthly donations to your favorite creators, sometimes in exchange for special perks (like early access to videos, a special Discord server, and so on). Patreon is now adding another feature creators can use - Stories.
It has become a running joke that apps continue to copy Snapchat's 'Stories' feature, where users post public pictures or video that only lasts for 24 hours. Patreon's implementation is called 'Lens,' and creators can choose to have their media visible publicly or only to backers. I can see this being useful in some circumstances, but it sounds like they will only be accessible through the Patreon mobile app.
If you want to download Patreon's mobile app, you can do so from the below widget.