Mutations: Captchas initially featured familiar words and typefaces but soon evolved into gibberish with distorted backgrounds. Then the words themselves began to warp and in some cases gave way to pictures.
Credit: Effat Emamian and Ali Abdi
Researchers mull the next step in spam deterrents.
Spammers use automated programs called bots to harvest online data, so in 2000, a group of researchers created a bot deterrent called the Captcha--the "completely automated public Turing test to tell computers and humans apart." The first Captchas required people to type in words displayed as images on a Web page in order to access a website.
But as bots have gotten smarter and Captchas more complicated, two problems have arisen. The first is that the Captchas can be hard for humans to solve, too. The second is that spammers have simply enlisted networks of humans to attack Captchas.
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