Captcha is known for being a spam prevention effective solution in regards to all forms of spam that can be done by bots. The reason for that lies in the fact that Captcha is a test that validates web users as human beings, just as the name implies: CAPTCHA = Completely Automated Public Turing test to tell Computers and Humans Apart.
What form of spam Captcha can prevent then?
Among others, Captcha is able to prevent forum spam, comment spam or spam in blogs, guestbook spamming and newsgroup spam.
Forum spam – What, How and Why?
Forum spam is a process of posting abusive advertisements or unwanted messages on internal forums, generally by spam-bots. It is done by inserting a link or dozens of links into the forums. The links come with minimum text and the content is mostly irrelevant to the forum but still it is inserted in hope that it will prevent spam filters from carrying out their mission. By adding links to the forum, the spammer strive to attract potential customers to its site.
Comment spam / Spam in blogs
Similar to forum spam, links that point to the spammer’s website are inserted into blogs using the section of comments given by the blog.
The one who is behind these comments spam is doing it in order to increase his site search ranking! Inserting as many links as possible, while using keywords as anchors, also increases the number of potential visitors or paying customers to the spammer’s site.
Guestbook spamming
According to Wikipedia, a guestbook is “a paper or electronic means for visitors to acknowledge their visitation to a site, physical or web-based, and leave their name, postal or electronic address (if desired), and a comment or note, if desired. It is used at museums, hotels, churches and so on”.
This applies to the web as well.
Web sites use guestbooks to display the type of visitors who visit the site as well as getting a feedback from the visitors about the site. (The visitor is not required to open an account and can leave a public comment).
Commercial website spammers may leave endless comments adding links to their site for the same reason mentioned before – increasing the number of potential visitors or paying customers to the spammer’s site.
Newsgroup spam
Newsgroup spam is a process of posting endless articles with faked and falsified article headers to usenet newsgroup in order to disrupt and make the newsgroup unreadable.
Can we fight against those forms of spam?
Yes. We can!
Since captcha demands the user to prove he’s a human being (by solving a simple test that humans complete easily) bots that run into the captcha test while trying to sign them selves up to all kinds of online platforms such as forums, guestbooks or blogs – are being stopped simply because they can not complete the test.
In other words -
Captcha is the perfect solution for online spam prevention!
August 1st, 2009 at 7:06 pm
[...] To understand what is reCaptcha we first need to define the term “Captcha”. Captcha is a test made of an image and distorted text that has to be solved by human users when they want to subscribe to websites that want to make sure the user is a human being and not a bot or a computer (= preventing spam). [...]
October 10th, 2009 at 6:19 pm
[...] been proved that captcha should be improved constantly if it’s into serving as a reliable spam blocker as well as a security [...]
November 20th, 2009 at 8:12 am
[...] about the future? No doubt that in the future comment spam prevention techniques will get more sophisticated just as well as new ones will be developed. This is due to [...]
May 31st, 2010 at 6:36 pm
[...] many users find Captcha annoying and irritating the use of Captcha test as a mean of spam prevention becomes more and more popular since there is no other absolute alternative way to stop those bots [...]
May 31st, 2010 at 6:44 pm
[...] What is captcha for? Captcha system is used on the online sphere as a method of verifying a user as a human being. Since some websites (such as forums & blogs for example) might be attacked by bot spammers sending endless garbage data, links or ads, they use captcha service as a mean of spam prevention. [...]