Carousel posts are an interactive and interesting way to show off your products or services. Your post appears with a few photos/videos that your audience can wheel through. You can add up to 10 photos/videos, and each of them can have their own headline, call to action and description. It means you can have up to 10 single ads in one advert unit.
You can use carousel posts to share your brand’s story, services, or products (as you need to scroll/click arrows to go to the next unit, it often looks like a story). Also, this form can be used for showing separate products or services as well as specific features of just one product. It’s up to you.
Although in the beginning they could be created only as adverts posts (for following adverts goals: website clicks or conversions, app installs or engagement, video views and Page post engagement), now you can also create them as regular Page posts.