Context filtering is like having mommy and daddy help you pick out the right story to read before bed. You have lots of books to choose from, but mommy and daddy know which ones are good for you and which ones are not.
Context filtering works the same way with information on the internet. There is so much information out there, but not all of it is true or appropriate for you. So, just like how mommy and daddy help you choose the right story, there are computers and tools that can help you choose the right information to look at.
These tools look at lots of different things like who you are, where you are, what time it is, and what you're interested in, to make sure you get the right information that you need. So, if you're looking for information about farm animals, the tool will filter out all the information that's not about farm animals, and it will only show you the information that's helpful to you.
In short, context filtering is like having a helper that makes sure you only see the information that's good for you and that you're looking for.