For questions about the CAPTCHA used on Stack Exchange sites to verify that you're a person and not a spam-bot.
CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is an anti-spam measure to prevent or reduce the effect of "spam bots" submitting junk to the site by presenting a problem that is easy for a human to solve but difficult-to-impossible for a computer. Some common methods are identifying "squiggly" letters, reading numbers from a slightly blurry photo, identifying an animal in a photo or drawing, simple arithmetic, and so on.
This tag is for questions about the CAPTCHA used on Stack Exchange sites.
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