Instagram adopted Snapchat-like Stories first, which were then rolled out on Facebook too. Text mode came on Stories on Instagram that was again rolled out on Facebook later. Basically, we are trying to establish the pattern.
Now, after Instagram received the feature to archive stories, sometime last year, the same has now been made available for Facebook users as well.
Essentially, if you use Facebook Stories, you will now see the Archive option on the top right, just above the row of stories. The feature lets you save a story without actually downloading it to your phone. So, if you put up a story and you want it to remain with you for longer than 24 hours, you can archive it.
You can re-use it in future if you want, or you could just keep it for memory for as long as you like.
Your archives cannot be seen by anyone but you. The folder saves up on Facebook, and will not take up any space in your device. If there is any story you archive, which by the way, could be both video or image, you will also have the option to delete it if you ever wish to.
Also, there is no limit to how long you can keep an image archived. Just remember to archive a post before it expires (24 hours).
Facebook had announced this feature back in May. Along with it, the platform also announced voice posts in Facebook Stories, which will basically let you share pictures with audio clips placed on top. But this feature is aimed primarily at Facebook Lite users.
Additionally, Facebook also said it will be releasing a feature, which will allow users to save the photos and videos they capture for later on Facebook, instead of saving it on the device. Sort of like a feed draft on Instagram.