CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) which is a security
challenge through which human and bots intervention can be measured. It is a type of turing test through which programmed
intervention can be detected by it behavior or solving the problem. There are various CAPTCHA problems available such as
distorted string, picture recognition, audio, math and gaming CAPTCHA. Game based problem is interactive and highly secured
as compare to the other CAPTCHA.