The term Captcha stands for ‘Completely Automated Turing Test To Tell Computers and Humans Apart’


‘A CAPTCHA is a program that can generate and grade tests that humans can pass but current computer programs cannot’ (Recaptcha, 2009).

Computers have become so common place, with the services they offer to humans. There has been a need for increased levels of security in the interaction between humans and computers to ensure that dealing with humans is secure and safe.

The process of using CAPTCHA happens when a digital transaction is occurring, CAPTCHA is used to validate the transaction. The user is presented with a distorted word, which is placed on top of a distorted background. The user then must type in the word in the given field to complete the process. This process is done because computers find it difficult to make sense of the distorted words, while humans can easily decode the distorted words. These days some CAPTCHAs use pictures in the process instead of words, but using words is more widely used.


ReCaptcha (2009) Telling Humans and Computers apart automatically [Online]
Available at: [Accessed on 23/03/10]

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License