How Do CAPTCHAs Work and Why Are They So Difficult?

You’re trying to purchase an item or log into an account. You enter your credentials, but before you proceed, you need to prove that you’re a human being. Tick the box marked “I’m not a robot”. You can see a blurred image with skewed digits that you need to decipher. These are CAPTCHAs, and while they can be a nuisance, they’re necessary.

Right? What are CAPTCHAs and how do they work? How are they different from reCAPTCHAs? And why are many of them so difficult?