Captchas offer a solution: voters should show they are human before being allowed to vote. . Capthca is an acronym for "Completely automated public Turing test to tell computers and humans apart". It is a type of test used by applications to tell whether or not the user is human.
A common type of captcha requires that the user type the letters of a distorted and/or obscured sequence of letters or digits that appears on the screen. Because the test is administered by a computer, in contrast to the standard Turing test that is administered by a human, a captcha is sometimes described as a reverse Turing test. 
Spammers have found a creative way to circumvent Captcha tests. First, the spammers open and advertise a Web site containing pornography. Visitors to the porn site are asked to enter the word contained in a Captcha graphic before they are granted access.
In the background, spammers have already used scripts to automate the Web mail accounts opening process to the point where they need a human to "read" the Captcha graphics. The Captcha graphics from the Web mail site are transferred to the porn site, where the porn consumers interpret the Captcha words. As soon as they enter the correct word, the script can complete its application process and the visitors are rewarded with free porn. 
I thought a Captcha would look great on a T-Shirt. So just for fun, I have made one such T-Shirt available from my store at Cafepress :) Drop me a comment if you know of a service equivalent to Cafepress in India.
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