驗證碼 (CAPTCHA / yànzhèngmǎ) is a challenge-response test used to ensure that the respondent is a human and not a bot. It usually comes in the form of a series of distorted characters that a person must successfully repeat by typing. CAPTCHA stands for “Completely Automated Public Turing test to tell Computers and Humans Apart.” In Chinese, it literally means “verification code.”
Why it is blocked: No idea. The whole phrase is blocked, not just the portion meaning “verify,” and I don’t know of any hidden meanings for the word. The simplified version of the characters (验证码) is not blocked. Any guesses would be appreciated. (Status - 1/10/12: blocked; 2/5/12: unblocked; 3/12/12, 3/29/12: blocked)
