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What Is CAPTCHA? |
By:
Oleg |
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What Is CAPTCHA?
by Oleg
"CAPTCHA", which is trademarked the Carnegie Mellon University, is a short form for "Completely Automated Public Turing test to tell Computers and Humans Apart". It is a test, which helps the computer to differentiate between machines and human beings. It has the capability of creating and grading tests that automatically accepts all humans and rejects all machines.
It works on the assumption that humans can read distorted machines but machines usually cannot do so. You can know more about CAPTCHA and smart CAPTCHA at http://www.protectwebform.com/ and http://www.protectwebform.com/smartcaptcha.
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.
CAPTCHA is a sure shot way of preventing these bots from creating havoc. The CAPTCHA asks the user to recognize the distorted image of letters and numbers usually with a string over a ?noisy? background. While it is easy for a human to decipher it, the machine usually cannot. And, that is how CAPTCHA distinguishes between a human user and a computer. Various large and small sites find CAPTCHA quite useful. No wonder, you see them in mail services, banking sites, blogs, chat rooms and similar places.
Spammers send unsolicited, undesirable and unwarranted messages in bulk to your inbox. Besides that, there can be other spam too in the form of usenet newsgroup spam, log spam, search engine spam and the like.
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.
On newsgroups, the spam is Usenet Spam. You may have seen this when you log into a newsgroup you enjoy. You may be trying to read a topic but see that is has been inundated with post after post of some sort of advertisement that doesn't belong there. That's Usenet spam.
There is another kind of email spam that targets individuals with direct messages. It scans postings from Usenet or pilfers from the Internet mailing list. This kind of spamming involves some expenditure.
Oleg is an expert on CAPTCHA design. Click to find out more about his new Smart CAPTCHA technology. Click here to get your own unique version of this article.
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Article Source: http://www.statssheet.com/articles/article53893.html |
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