Ontology is like a giant filing cabinet where computers store information about things in the world. Just like you have a drawer for socks and a drawer for shirts, computers organize information into categories like "animals" or "plants" so they can find things quickly.
Think of it like playing a game of 20 Questions. You ask a series of questions to try and guess what someone is thinking of. In computer science, the computer asks a series of questions to try and understand what something is.
For example, if the computer wants to understand what a "dog" is, it might ask questions like "does it bark?" or "does it have four legs?" based on what it already knows about animals.
The ultimate goal of ontology is to help computers understand the world in a way that humans do. This makes it easier for computers to perform tasks like search engines or recommend products.