What is a system?

System Analysis and Design:

What is a system?
System is a collection of components that work together to realize some objectives.

Explanation:
Generally a system is a collection of components. These components can be anything that made the system, either physical components or non-physical components such as procedures, methods, rules and regulations, theories, etc.

Look at a car for example! How many parts are there? There are thousands of small parts from small nuts & bolts to large wheels, tires, etc. These are the components of a system.

A system can also contains components that can be considered as sub-systems. As an example, the engine of a car is another system in the car system. Therefore a system can be made of subsystems with other components as well.