true to attempt to marshal the continuation back to the original context captured; otherwise, false.
It’s actually more like saying that ConfigureAwait(true) is like using .ContinueWith( t => {...}, TaskScheduler.FromCurrentSynchronizationContext()), where ConfigureAwait(false) is like using .ContinueWith( t => {...}). If you pass false, then the continuation is being allowed to run on a thread-pool thread instead of pulling back to the current synchronization context.