CAPTCHA, short for Completely Automated Public Turing test to tell Computers and Humans Apart, is a security mechanism used to distinguish between human users and automated bots or scripts by presenting challenges or tests that are easy for humans to solve but difficult for machines to pass. CAPTCHA challenges typically involve distorted text, random characters, images, puzzles, or simple tasks that require human perception, reasoning, or interaction to complete, such as typing alphanumeric codes, selecting images with specific objects, or solving mathematical problems. CAPTCHA helps prevent automated bots from abusing online services, websites, or web forms for malicious activities, such as spamming, scraping, fraud, or account takeover, by verifying the user’s identity or intention before granting access or performing actions.
