Continuation Nexus

Continuation:
A concept invented along with the subroutine, but unnamed then. The continuation is the system’s record of what to do after the code in the subroutine has finished. Today the continuation is usually embodied in the stack. The continuation is explicitly accessible in Scheme and introduced here in the language definition. If the routine is to produce a value then the continuation is waiting for that value to proceed. Even when no value is returned the continuation may need to wait until the actions of the subroutine have been performed. See the Wikipedia too.