Okay kiddo, so ISO 1 is a standard that helps make sure things are done in a really clean and safe way. Imagine you're playing with your toys and they get all dusty and dirty. You want to clean them so they're nice and sparkly again, right? Well, ISO 1 is kind of like cleaning your toys, but on a much bigger scale.
You see, some grown-ups work in places where it's really important to keep everything super clean and free of germs. This could be in a hospital, a laboratory, or even a factory where they make medicine. The people who work in these places have to be very careful not to bring in any germs or dirt from outside, because that could make the people who go there very sick.
So, ISO 1 is a set of rules that these grown-ups follow to make sure everything is as clean and safe as possible. They wear special clothes and shoes that don't have any dirt or germs on them, and they use special machines and tools to clean the air and surfaces. They even have to be very careful when they talk, because spit and breath can have germs in them too!
Basically, ISO 1 is like a big list of rules to help grown-ups keep things clean and safe in places where it really matters. And it's all to help make sure people don't get sick and can stay healthy!