CAPTCHA, or Completely Automated Public Turing test to tell Computers and Humans Apart, is a term used to encompass technological tools used to differentiate humans from computers during online interactions–usually with a focus on preventing automated computer systems from abusing email services, repeatedly trying to enter passwords, or otherwise creating undue strain or security problems for networked services.
A common type of CAPTCHA involves asking the user to type out a series of distorted and cross-hatched letters and numbers. Identifying distorted letters embedded in an image is something human beings can do easily but computers find quite difficult. Unfortunately, as computers and CAPTCHA cracking algorithms become more sophisticated the CAPTCHAs themselves become more distorted and difficult for humans to decode. Security specialists are in a continual race to search out new CAPTCHA techniques that prevent bot-drive abuse without locking out legitimate users.
- By Jason Fitzpatrick on 03/5/13