How Useful Is CAPTCHA?

By: Oleg..

What is CAPTCHA? It stands for Completely Automated Public Turing test to tell Computers and Humans Apart. It is a test that assists a computer in telling the difference between humans and machines, that has been trademarked by Carnegie Mellon University. With CAPTCHA a computer can detect whether a machine or a person completed a test, and discard any computer answers.

It gives you a test to decipher distorted numbers and letters, which are pretty easy for a person to do, but cannot be figured out by a machine. For further details about CAPTCHA and smart CAPTCHA go to and

CAPTCHAs are really useful. They help preventing programs known as bots. Bots are programs that pretend to be humans and abuse the services of the internet. Bots usually have the intention to sell or make you sign up for thousands of free mail services. The bots spam your inbox daily. They penetrate common chat rooms with the intention of accumulating personal information and publishing links to various sites for promotional benefits.

The bots crack your passwords, encroach upon your privacy and use your personal information for commercial use without your permission. They create worms that can cause immense harm to your machine.

CAPTCHAS and CAPTCHA plug-ins ( intend to prevent these bots from creating havoc. The CAPTCHA programs need the user to recognise and then key in a string of distorted letters and numbers in a box. The string will appear as a distorted image over a ‘noisy’ background. CAPTCHAs are used by various large and small sites. You will find them in mail services, banking sites, blogs, chat rooms and similar places.

Spam seems to unfortunately be way of life. Day in and day out spammers are sending message after message into your e-mail system. But it's not just in e-mail that you may be hit with spam. Spam also is a problem in online newsgroups, logs, search engines and even instant messaging!

Some advertisers think spam is a good way to go to get their message out to the masses. It doesn't really cost them anything other than finding lists of e-mail addresses to send to, so they send mass amounts of mailings, and there is nothing you can do about to stop it, because laws do not allow holding a sender responsible for the number of mailings they send on the internet.

Usenet spam is a message that can be sent to twenty or more Usenet newsgroups. This kind of spam floods the newsgroups with unnecessary advertisement and posts. It also challenges your ability to accept and manage the topics on the system.

The other kind of spam, which is the email spam usually targets individuals with direct messages. The list of ids that are targeted to spam can be created by scanning postings from Usenet or pilfering with the Internet mailing list. This kind of spamming does incur a little more money.

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Oleg is an expert on CAPTCHA design. Click to learn more about his ingenious new Smart CAPTCHA technology.

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