In systems thinking or systems dynamics, we define a system as follows;

• It consists of some elements.
• Those elements are interrelated.
• It has a particular goal or function.

If something satisfies the above conditions, that is a system

Please look around you and find some systems.
Company is a system. Government is a system. School is a system. Transportation is a system.
Family is a system. Cooking is a system.

Now you are aware that we are surrounded by systems.
Even our body is a system.
You also notice that some systems work well but others do not.