The Alagad Captcha is a ColdFusion Component written in native ColdFusion which generates images of obfuscated text. The text is intended to be human readable but not machine readable. By comparing a user provided String to the known value of the string displayed in the image, you can confirm that a human, not a computer, is interacting with your application.
Captcha is an acronym for "completely automated public Turing test to tell computers and humans apart". Captcha images tend to be used on web forms to Prevent automated submission by computers.