What scope do coroutines run in by default?

Coroutines in Kotlin run in the "Default" scope by default, which is designed for CPU-bound tasks. When a coroutine is launched without explicitly specifying a scope, it inherits the context from the caller, and if none is provided, it operates within the Default dispatcher. The Default dispatcher optimally utilizes available threads for executing coroutines and is a good fit for tasks that require computational resources but don't involve blocking I/O operations.

This scope is particularly beneficial for executing operations that are parallel and computationally intensive, allowing for concurrent execution. It effectively manages threading for standard workloads, ensuring efficiency in handling multiple tasks simultaneously by managing a shared pool of threads that can be reused.

Other options, such as the Main scope, are specifically meant for UI-related tasks, while the IO scope is optimized for offloading blocking I/O operations. The CoroutineScope option isn’t a dispatcher itself but rather a context used to build coroutine builders, which means it's not directly answering the question regarding the default operating environment.