Turing Number

Abbreviated as TN, turning number is a randomly generated security code, usually a series of digits, displayed as an image that users may need to read and copy into a form field in order to submit or validate a form submission online via a Web browser. Turing numbers are used to ensure there is a human user instead of automated (bot) submissions. Turing numbers are commonly used on e-commerce Web sites or promotional or contest Web sites —anywhere there is a need to avoid automated submissions by bots.