In today’s world of excess spam and “bot” (robot) traffic, one line of defense is using CAPTCHA. CAPTCHA (Completely Automated Public Turing Test to tell Computers and Humans Apart), as the expanded version of the acronym implies, is frequently used to tell computers and humans apart.

A CAPTCHA usually features an image that is slightly distorted and is made up of aplhanumeric characters. A human can quite easily read the image, but a “bot” cannot. A “bot” can recognize that the content contains an image, but it cannot tell what the image is.

Once a user types in the word(s)/number(s) in the CAPTHCA they are given access to the information.

The most common uses of CAPTCHA are to stop “bots” and other automated programs from:

• Using Blogs - Bots tend to log onto blogs and fill them with spam comments.
• Affecting Search Enging Rankings - Bots can affect rankings by creating false traffic to your site.
• Signing Up for Email Accounts - Bots sign up to email account providers and send spam … “I really don’t need any more Viagra.”
• Signing Up for Online Polls - Bots can skew the results by voting multiple times.

Therefore if you are setting up a blog, online poll, or email account on your website - I would recommend using CAPTHCA if you wish to reduce the amount of spam or “bot” traffic.