TestFlight is a service Apple acquired a few years ago that is fully integrated with iTunes Connect. It lets you test your iOS apps before you release them on the App Store, with a select group of beta testers.
Beta testing is important because it gives developers the ability to gather feedback on their app as it is being used in real-life situations, and discover bugs they might not have caught otherwise.
There are two kinds of tests you can run with TestFlight: Internal and External tests.
In an Internal test, users within your team who have been assigned a Developer or Admin role in iTunes Connect can privately test the app, allowing you to gain feedback from them quickly. Up to 25 users can be part ...