CAPTCHAs???

                                                                         

Try to recall the first time you registered for a Grail account. You went through the “required” fields pretty fast and towards the end just before clicking the Submit button, I bet you came across something like this:

 

This “Word Verification” can be a very annoying task especially if the characters are distorted!!!

Have you ever wondered what this is and what purpose does it serve?? Here’s the answer.

The image above is a typical CAPTCHA(Completely Automated Public Turing test to tell Computers and Humans Apart). It is a program that is used to detect whether its user is a human or a computer. Thus its main aim is to generate tests that humans can pass and computers cannot pass.

But why would this be necessary?

Consider the following example:

·         A company organizes an online poll to find out which sites its clients visit frequently.  The results of the poll are then used to decide which channels would be preferred for marketing campaigns. If a person writes a program to vote for a particular option a thousand times then the results of the poll might be meaningless. If a CAPTCHA is used in this case, the program might not be able to detect the correct characters each time in the CAPTCHA and hence those votes would be invalid. Although this might not ensure complete security from bots(automatic voting programs), the accuracy of the poll will be improved.

 

Different types of CAPTCHAs are now being used to prevent detection by bots. The characters could be blurred or with different backgrounds, making them difficult for bots to detect. CAPTCHAs could involve selecting the right image or sometimes even playing a game!

CAPTCHAs are also used to prevent Comment Spam in blogs, protection of email addresses etc. Sites that use CAPTCHAs are Gmail, TicketMaster, Flipkart and many others that need to verify identities.

Kimberly D’souza

St. Francis Institute of Technology