What are reCAPTCHA and CAPTCHA and why do I keep seeing them?

If you’ve ever been online and had your surfing interrupted by a test asking you to “Click all the traffic lights” or “Type in these wonky letters”, you've encountered CAPTCHA.

While it may seem like an annoying roadblock between you and wherever you’re trying to go, CAPTCHA serves an important function: protecting the internet from bots and spam. If you’d like to find out what CAPTCHA – and its younger cousin, reCAPTCHA – is, why it keeps popping up, and how to navigate it (almost) painlessly, this article is for you!

By Alyssa Schmitt

What does CAPTCHA mean and what does it do?

First off, let’s define CAPTCHA:

CAPTCHA is a challenge-response test used on websites to figure out whether a user is a human or a bot.

Why do we have CAPTCHA tests? Because of the need to protect websites from bots, which are automated programs that can wreak havoc on the internet. For example, bots can be programmed to:

• Spam comment sections of websites with advertisements
• Flood online forms with fake submissions
• Steal data from websites using automated scripts

CAPTCHA acts as a gatekeeper to this sort of bot activity by asking for an action or a response that could not be preprogrammed – performing it correctly is a way of proving that the user is indeed human.

You may have seen different sorts of CAPTCHA tests, e.g.:

• Text-based CAPTCHA: You are shown a series of distorted letters and numbers and have to type them out.
• Image CAPTCHA: You see a grid of photos and have to click on certain images such as bicycles or crosswalks.
• Audio CAPTCHA: For users with visual impairments, an audio clip is played with numbers or words that need to be typed out.

mail.com uses CAPTCHA tests to prevent bots from registering fake email accounts and spamming our online contact form. So, if you sign up for an email account with mail.com, the registration process includes a reCAPTCHA checkbox.

What does the CAPTCHA acronym stand for?

If you had ever even heard the word “CAPTCHA” before reading this post, you may have wondered whether it is a made-up word or an abbreviation or what? (Personally, the first few times I heard it, I thought people were saying “capture,” which was confusing...) “CAPTCHA” is an acronym that stands for “Completely Automated Public Turing test to tell Computers and Humans Apart”. Because of course it does!

This immediately raises a further question of what the “Turing test” part is all about. It’s named after British computer scientist Alan Turing, who designed a test to determine whether a machine could exhibit intelligent behavior indistinguishable from a human. CAPTCHA is a modern application of his idea.

If you'd like to learn about the difference between CAPTCHA vs. reCAPTCHA and get tips for dealing with CAPTCHA tests, you can read the full article here!