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What Is CAPTCHA?
"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.
“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.
The reason why advertisers resort to spamming is because it does not cost much. They have to bear only the cost of managing the list of individuals that are targeted to receive the mails. Moreover, you cannot hold the sender accountable for the mass mailers they send. Spamming has become really ubiquitous since there are no entry barriers. No wonder your inbox is always flooded with mass mailers.
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.
Another kind of spam, which is a little more expensive, is the instant message spam. In this case, advertisers have paid a little more to get a hold of a list of instant messaging ID’s and then sent messages directly to those people.