Okay, so let's pretend you have a bunch of different toys in your toy box. You want to organize them so you know which toys are for playing with in water, which ones are for playing with outside, and which ones are for building things with. That way, when you want to play with a specific type of toy, you know right where to look! This is kind of like the Anatomical Therapeutic Chemical (ATC) Classification System.
Doctors, pharmacists, and scientists use the ATC system to organize different medicines. They want to be able to know which medicines treat certain illnesses, which ones are safe for certain groups of people, and which ones might cause side effects. Just like you organize your toys, they want to organize medicines so they know which ones to use when they need them.
The ATC system sorts medicines into groups based on what parts of the body they treat (the “anatomic” part), what illnesses they are meant to cure or prevent (the “therapeutic” part), and how they work (the “chemical” part). For example, if a medicine is meant to help with pain in your joints (anatomic), it will be classified into a group of medicines that treat joint pain (therapeutic), and it might contain a chemical that helps reduce inflammation (chemical).
This might all sound really complicated, but it's actually a really helpful way of sorting medicines so that doctors and pharmacists can make sure that they are giving patients the right medicine for their specific illness. It's like having a really organized toy box, but for medicine!