Answers
Nov 23, 2015 - 05:15 AM
A CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot.Humans can read distorted text,but computer programs can not read it.
Nov 23, 2015 - 05:15 AM
The captcha is a visual or audio challenge to the user to prevent bots and automated scripts from accessing the services protected by it.
It is valuable for:
--> forums that want to prevent spambots/adbots from signing up --> protecting downloads from automated access by bots (which is not a security risk in itself, but a bandwidth drain) Google uses it for search queries if there have been excessive numbers of queries from a single IP adress
A CAPTCHA does not provide any other kind of security, it only provides protection from bots and the rate limiting that comes with it.
