Although most CAPTCHAs are letter pictures randomly generated, many of them have become difficult even for a human to read , so picture CAPTCHAs were created in which a human is shown a simple test to show a picture of a certain animal (given few animal pictures), which is simple for a human being to process, and therefore easy to pick, while a bot cannot process and solve the question because although it can analyze the picture, it cannot easily guess the animal.