The initials for Captcha are: “Completely Automated Public Turning test to tell Computers and Humans Apart”.

But when searching for the term on the web it seems like users tend to perform some typing errors as well as misspellings.

The most common misspellings for the captcha term are: captsha, capatcha, capttcha and chaptcha, while sometimes these misspellings are used also as plural forms.

Nevertheless, Captcha is a short task that comes to distinguish between a real human user and a bot or an automated machine, in hope to avoid spam and other abuses on the web.