[Coder1996]

I asked ChatGPT 4 for an explanation and came up with this analogy,

Imagine all in-game characters have their data in a database. The database might have one or more tables representing an objects ID or another reference, its position, its health points, and image data representing how to draw the object. These three things are "components" and the IDs and references are "entities."

A system is anything that manipulates one of these components. Thus, a function that manipulates a component is a system.