Simple Definition:

A system is a group of interconnected parts that work together to perform a specific function or achieve a particular goal. Each part has a specific role or function, and they rely on each other to work properly.

For example, a computer system includes components like the monitor, keyboard, and CPU [the part of the computer doing the “thinking”]. Each part has a specific task: the monitor displays information, the keyboard allows input, and the CPU processes data. Together, they allow us to use a computer to browse the internet, play games, or create documents.

Very Simple Definition:

A system is a group of things that work together to do something.

For example, your digestive system is composed of the different organs [parts of your body] that work together to digest [break down] food.