Kernel

Now, think about a tiny magnifying glass. Imagine using this magnifying glass to look at small parts of your coloring page. You notice interesting details like a butterfly's wings or a flower's petals.

In the world of computers and AI, this magnifying glass is what we call a "kernel". A kernel is a tiny matrix that moves over the image and helps the computer understand little parts of the picture at a time. The computer can use this to recognize patterns or features, like the edge of a butterfly's wing or the round shape of a flower.

In depth reference can be found here