CAPTCHA is very often used as a method to reduce the number of spam comments on websites. It is a way to verify that the person who leaves a comment is real, and is not an automated script. For those who do not know, CAPTCHA is a type of challenge-response test used in computing to determine whether the user is human. “CAPTCHA” is an acronym for “Completely Automated Public Turing test to tell Computers and Humans Apart”, and it is often incorporated it in a way that visitors have to type the letters of a distorted image. Most spam comments are posted by bots or programs which are specifically designed for spamming. They automatically visit sites on the Internet to look for places where it is possible to submit comments. They do this in order to post unwanted advertisements of websites or services. One of the best ways to stop these bots is to use the CAPTCHA system which requires the visitor to write down the letters that he sees. Since computer programs do not know how to analyze images, only humans will be able to decipher the letters. While some CAPTCHA’s have been broken like phpBB’s, it is still a very good method to avoid scripts spamming forums or other websites. A lot of sites are recently adding the CAPTCHA verification system. I think that this will not make them necessarily less enjoyable to visit, but will rather prevent spammers and hackers. However, when using CAPTCHA it is important to make it readable to for average person. After all, we want to stop bots from visiting our site, not our loyal visitors.