Behavior of co-operating processes is nondeterministic i.e. it depends on relative execution sequence and cannot be predicted a priori. Co-operating processes are also Reproducible. For example, suppose one process writes ―ABC‖, another writes ―CBA‖ can get different outputs, cannot tell what comes from which. Which process output first ―C‖ in ―ABCCBA‖. The subtle state sharing that occurs here via the terminal. Not just anything can happen, though. For example, ―AABBCC‖ cannot occur