A system has following three characteristics-

1. It has more than one element.

2. All elements of a system are logically related.

3. All elements of a system are controlled in a manner so that the goal of the system is achieved.

Hence, we can say that-

A computer is a system as it comprises of integrated components (Input Unit, Output Unit, Storage Unit and Central Processing Unit) that work together to perform the steps called for in the execution of a program.