Do You Need CAPTCHA?

By: Oleg..

CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart. Developed and trademarked by Carnegie Mellon University, the job of this test it to know if it's a person or a computer trying to access your system or website. Read more about CAPTCHA at

A CAPTCHA requests the user to take a test. Any user who provides the correct answer is considered to be a human. A very common instance of a CAPTCHA is to ask the user to key in letters from a distorted image. The sequence includes alphabets and numbers. If the user keys in the correct sequence, he is considered to be a human or else a machine. A smart CAPTCHA is pretty easy to implement. You can get the details from

Website owners have to guard against spammers yet they need feedback from the visitors to their site. Spammers are always on the look out to grab your email id and use it for various purposes without your permission. One option is that you can go in for automated programs, called bots, to let them scan your website and parse out your mail id.

CAPTCHA ensure that the spammers do not get access to your email ids. Many websites and sign up pages use CAPTHCA Plug-in ( The distorted messages that the user has to type in ensures that the user is human. CAPTCHA assumes that computer programs cannot read distorted characters.

CAPTCHA has become very popular in the past few years because it is a program that can create tests which only humans can clear. Since the program is fully automated there is virtually no chance of any human intervention. No wonder, most website owners go for it.

Spammers are a nuisance. Once they get hold of your email id, you are bombarded with spam mails and you can never be sure what your id will be used for. This is where CAPTCHA comes to your rescue by preventing abuse of your system.

CAPTCHAs not only prevent encroachment by spammers for commercial purpose, it also protects the systems that are gullible to spam like, the webmail services of Gmail, Hotmail, and Yahoo. They also help prevent automated postings on online blogs. There are some services which might allow automated use but within a limit. In such a scenario CAPTCHA helps in enforcing a usage policy and prevents any kind of deviation from the policy.

There have been numerous efforts at creating CAPTCHAs that are handier. Such endeavours usually include the use of JavaScript, mathematical questions (like "what is 1+1"), or simple questions requiring common sense (for instance "what color is the sky"). These attempts infringe on one or both of the philosophy of CAPTCHAs. Either they cannot be automatically created or they can be easily split given the condition of false intelligence. So, the only security these CAPTCHAs provide is safety through obscurity.

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The author, Oleg, is an expert on CAPTCHA design and development. Click to learn more about his revolutionary new Smart CAPTCHA technology.

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