CAPTCHA (short for Completely Automated Public Turing test to tell Computers and Humans Apart) is a security feature that checks if you’re a human — not a bot.
It was created in the early 2000s as a way to prevent spam and abuse on websites. CAPTCHAs are those little tests you’ve probably seen: typing distorted letters, clicking on traffic lights, or checking a box that says “I’m not a robot.” They help block fake signups, brute-force attacks, and scraping tools by making sure there’s a real person behind the screen.
Why do we still use CAPTCHAs?
Because bots keep getting smarter — and CAPTCHAs are a moving target. Early ones used warped text. Today, we have invisible CAPTCHAs, behavior analysis, and image-based puzzles that are harder to fake. While some people find them annoying, they’re still one of the simplest and most effective ways to keep websites safe.
Curious about how they work (and how they’ve evolved)? Check out this intro by Cloudflare
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