Answer

Calling `.cancel()` on a `CoroutineScope`:

1. Cancels all active child coroutines launched within that scope.
2. Cancels the scope itself.
3. Irreversible: Once a scope is cancelled, you cannot launch new coroutines in it. Any attempt to `launch` or `async` in a cancelled scope will throw a `CancellationException` (or simply be ignored depending on implementation, but effectively the job is dead).

Best Practice

• Only cancel a scope when the component associated with it is being destroyed (e.g., `onDestroy` in Activity).
• If you want to cancel children but keep the scope alive (e.g., user cancels an operation but stays on the screen), cancel the Job of the specific coroutine or use `coroutineContext.cancelChildren()`.

```kotlin // Cancel children but keep scope alive scope.coroutineContext.cancelChildren() ```