What are Flutter Flavors and how are they used?

Flutter Flavors allow you to build multiple variants of the same app from the same codebase — typically dev, staging, and production. Each flavor has its own app ID, display name, app icon, Firebase project, and API base URL. On Android, flavors use Gradle's product flavors. On iOS, they use schemes and targets in Xcode. You define flavor-specific Dart constants via --dart-define flags. This is essential for professional app development where you need separate apps for testing without affecting production users.