How to break a CAPTCHA system in 15 minutes with Machine Learning

CAPTCHAs were designed to prevent computers from automatically filling out forms by verifying that you are a real person. But with the rise of deep learning and computer vision, they can now often be defeated easily. I've been reading the excellent book Deep Learning for Computer Vision with Python by Adrian Rosebrock. Adrian didn't have access to the source code of the application generating the CAPTCHA image. To break the system, he had to download hundreds of example images and manually solve them to train his system.