Receptive Field

Imagine you're at a zoo looking at a large, wide cage filled with all sorts of different animals: lions, zebras, giraffes, elephants, etc. But instead of seeing the whole cage at once, you're looking through a small hole in a big cardboard. You can only see a small portion of the cage through the hole.

This hole and the part of the cage you see through it is like a "receptive field" in a neural network. Just like you can only see a small part of the animal cage at a time, each neuron in the first layer of a neural network also 'sees' or 'focuses' on a small part of the whole image at a time.

By moving your cardboard around, you get to see different parts of the cage, right? Similarly, by moving across and down the image, the neural network can see different parts of the image. Over time, by piecing together all these little parts it has seen, the network can understand and recognize the whole picture!