@JvmStatic val Default: CoroutineDispatcher (source)

The default CoroutineDispatcher that is used by all standard builders like launch, async, etc if no dispatcher nor any other ContinuationInterceptor is specified in their context.

It is backed by a shared pool of threads on JVM. By default, the maximal number of threads used by this dispatcher is equal to the number CPU cores, but is at least two.