Okay kiddo, imagine you have a toy box filled with all your favorite toys, but some toys you don't really like or don't use very often. Now imagine if some grown-up took those toys you don't like and gave them away to other kids without asking you. That's kind of like what greynet is. Greynet is when someone takes your computer's resources or internet connection and uses it for something that you didn't agree to, without your knowledge or permission.
It's like when you share your juice box with your friend, but someone took your juice box and gave it to a bunch of other kids without you knowing. When someone does this with your computer or internet connection, it can slow down your computer or internet, and you might not even realize it's happening.
Greynet can happen when you accidentally install software on your computer that secretly uses your resources, or when someone else accesses your computer or internet connection without your knowledge. It's important to always be aware of what software you are installing on your computer and to keep your passwords safe and secure, so no one else can access your computer or internet without your permission.