Simply put, one app for one event.
When creating a new Single Event App, you must configure it with basic information such as a name, supported languages, and expected number of attendees. Note that what you enter at this stage does not need to be final—you can edit the basic properties any time before you publish the app. You can customize the Single Event app's icon that appears in the device home screen.
The appearance of your app is controlled by group of settings referred to as the brand. By editing the brand you can change the interface colours, and the images for the event logo, app background, splash page, and icons.
Once your Single Event App is configured and contains at least some test content, you can test it by creating a build and downloading it to a test device.
Publishing the app makes it available for download by attendees. Be sure that your app is correctly configured before you publish it, as once published some app properties and settings are difficult to change.