See you later, simulator

Simulation (or modeling) programs mimic a physical process; the process being simulated can be treated as discreet (occurring at points in time) or continuous (always occurring).

Simulation programs are similar to process control programs, except that they have two "clocks":  a simulation clock which records the time expired in the simulated process and a real-time clock which records the time taken by the program in the real world.
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Control: you must learn to control

Computer programs that control non-computer-related devices are called process control programs; programs that keep track of what devices are doing are called process monitoring programs.  Process monitoring and control programs usually run on their own processors and run continuously (or as long as the physical process is running).

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