Perhaps you want to have both a native mobile app and a desktop application? Maybe you application has different buyers and sellers, or you're a restaurant with customers, you have organizations and donors. Any situation where you want to create multiple applications for these users with the same database collections, you can share the databases.
IMPORTANT: A database can only be shared from one app to another at the onset of the second app's creation. The process will share all of the collections from the original application. Any and all edits made to the database will be shared from app to app.
Database sharing can be done from any application type, mobile or web, to the same or other and can be shared to any number of applications.
Create a New App
Choose either mobile or web app
Choose your template
Create your name and set your branding
Click advanced options
Select Share Database with Existing App
Choose the app with the database to share
Notice your database collections are now showing in the new app