A CAPTCHA is a visual perception task used as a security measure in the form of an online test. Humans but not computers are able to pass this test.

Computer scientists worked out that the easiest way to deceive spammers is to use images of letters and numbers. A manipulated image of text randomly generated so you can barely read it, but a computer trying to take a picture of it cannot.

We seem to be faced by these wherever we go on the internet, these twisted words and numbers that pop up whenever we need to post something, add a comment or blog!

Even though we read words on the internet, computers are not made of words. Computers often have a hard time understanding languages because they do not conform to the hard and fast rules that computer programs demand.  

CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart.

So what exactly is a Turing test? A computer theorist named Alan Turing invented the Turing test which humans use to see if a machine can converse like a human being.

Images are harder to have an exact answer for. This is why CAPTCHAs don’t use images of things other than letters or numbers. You can imagine the wide variety of responses of a random image. Letters are far easier to decipher by the human eye and accurately programmed by whoever creates the CAPTCHA.

So there you have it.... Just when you thought computers could do everything!

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