Edges are the pixels where the sight color of the pixels dramatically changes from one side to the other. For example, let's look at the following image:

The edges in the preceding screenshot are where the pixel color changes dramatically, such as from green to the hair color—blonde. For the flower, it will be exactly where the color will dramatically change for the first time from green to pink. On the right-hand side, we can see the output that we'll get after running the edge detection application. Hence, we can see the hands, the flower, the colors, the eye, and places where the color changes from up to down.