Human Test

Lot of sites ask you to type the characters you see in an image in their form submissions. For example, to put a comment on this blog, you need to do the same.
This test is called CAPTCHA. Its a technique to test for humanity, i.e. it makes sure that a human is filling the form and not some computer bot (automated code).

However, my experience with CAPTCHAs so far is that most of the times it is a test for humans with a 20/2 vision and IQ > 200. Most of these images are done so badly that I am unable to figure out what the text is supposed to be.

Don't believe in what I say? Check out this link for some of the unreadable CAPTTCHAs out there.