I am not sure exactly what CAPTCHA stands for, but the “T” stands for Turing and the “H” stands for Human. We all know what it is: when you sign up for something and you have to provide a translation of some garbled image. It’s a test of some kind that guarantees you are working with a human and not a machine. That’s the first big step of defeating spam.

The problem is that for large organizations with a wide reach (political campaigns) these types of systems have to be enormously sophisticated. If you are visually impaired, you might fail a visual CAPTCHA test. Generally you need to provide for that, possibly by providing an aural captcha.