Dropbox's Carousel is a smarter photo gallery which is used to backup photos and videos. If you want to free up space on your phone, then you can use Dropbox's Carousel to store and organize your photos. All your photos and videos in Carousel are stored in your Dropbox account. The only limit to the number of pictures you can put in your Carousel is the amount of space in your Dropbox. You can add up to 1TB of photos and videos in Dropbox Carousel, if you have a 1TB Pro account.