The Dry Bones Blog: The annoying "prove you are a human being by showing that you can read messed-up letters" is called a CAPTCHA, which is an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart". The "Turing test" is a fascinating test
proposed by Alan Turing in 1950, and important to computer scientists, theorists, and dabblers in Artificial Intelligence. You can read about it at Wikipedia's entry about, Turing test, Source: The Dry Bones Blog
