Saturday, November 27, 2010

Why do I have to copy weird text from a box when filling in a form on a website?

The warped text shown just above the submit button on a website is called a ‘CAPTCHA’.  Some websites ask you to type out the distorted text shown in a CAPTCHA box to prove that you are a genuine human being and not a malicious bit of software (a.k.a a ‘bot’).  The human eye can easily decipher the text shown in a CAPTCHA box, whereas software can not.  Unless CATPCHA text is correctly entered the submit button on a form won’t work, therefore if a bot can’t read the text then it can’t submit the form.

If websites didn’t ask you to take a moment to ask you to prove you are human the organisations behind them would be left open to (at worst) a cyber attack and/ or (at best) a large amount of spam from automated sources.

CAPTCHA forms also help protect websites from brute force attacks whereby a bit of code is used to repeatedly submit a form until the website breaks, and (sometimes) exposes confidential information.
So by taking a moment to copy the text you see in a CAPTCHA box before submitting information on a website you’re helping organisations protect themselves from hackers and spammers.

More about CAPTCHA
http://en.wikipedia.org/wiki/CAPTCHA
http://www.captcha.net/