There are few things in the world that I hate too much. One such thing is to prove a stupid computer that I am really a human , not a bot. The way we have to prove it, is so much annoying. Most of the time we have to read some distorted letters and enter them to a text box. This text is called a "CAPTCHA". "CAPTCHA" stands for "Completely Automated Public Turing test to tell Computers and Human Apart". This is a kind of Turing test. Instead of administrated by a human and targeted at a machine "Captcha" is administrated by a machine and targeted for a human. The "Captcha"s are used for variety of purposes. The main purpose is to stop spams and automated votes in voting systems. Most of the time we encounter these while registering to a website or posting a comment on a blog post. Also sometimes we have to fill a "Captcha" if we incorrectly entered a password several times.
But I feel this has become a very annoying thing to most people. Some of the "Captcha"s are really unreadable. It is interesting to know whether there are any data available on the time that is wasted due to these "Captchas". Thus the balance between the security and the user friendliness should be maintained by carefully selecting when to use "Captcha"s and their hardness to solve .