Apple has new features for iOS 14 for the iPhone and iPad, and the corresponding series of updates for developers. Want to take advantage of the new home screen widget to surface dynamic info or app clips to show off your app in miniature form, download the latest SDK and get to work.
So, you're trying to share some files with someone who only has access to an old version of Word. Or maybe that Microsoft-hating friend of yours who only uses WordPerfect. Perhaps you want that old-school ebook to be an epub, rather than .lit. For any of these problems, there are desktop apps that work, of course. However, sometimes you want to be able to do that within a program. If so, Doxument and the beautiful Doxument API are what you need.