Captcha
CAPTCHA is a challenge-response test used to tell a human user apart from an automated script before an action such as login, registration or form submission is allowed.
What is Captcha?
Definition
CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a challenge placed in front of an action — login, registration, form submission — to separate a human user from an automated script. Modern implementations rely less on distorted text and more on behavioural and device signals, precisely because image and text puzzles became cheap to solve at scale. Its role in cybersecurity is narrow and worth stating plainly: it raises the cost of bulk automation such as credential stuffing and spam, and it is not an authentication or authorisation control.
Role in cybersecurity
Captcha plays an important role in building organizational resilience against cyber threats. Implementing appropriate mechanisms in this area is required by regulations such as NIS2, DORA and ISO 27001.