Original: In computing, a process is an instance of a computer program, consisting of one or more threads,  that is being sequentially executedKnott 1974, p.8 by a computer system that has the ability to run several computer programs concurrently.
Simplified: In computing, a process is an instance of a computer program that is being sequentially executedKnott 1974, p.8 by a computer system that has the ability to run several computer programs concurrently.