could be textures, it could be edges, it could be curves, corners, etc. And what these filters are doing are constituting little miniature versions of each of these little building blocks. And the way that the CNN looks for these building blocks is the C in CNN, and it stands for convolution. It's a mathematical operation that looks pretty complex. But, actually, it's very simple. It's a very simple concept. It's kind of like you've got this filter, and you're walking to every part of the image, and you're just asking the question, how much does this image look like that filter?