What is the purpose of a CAPTCHA?

• A. To secure a website against cyber attacks
• B. To determine whether the user is human or a bot
• C. To encrypt passwords for safety
• D. To compress data for faster loading

Answer: (B)

A CAPTCHA, which stands for "Completely Automated Public Turing test to tell Computers and Humans Apart," is designed to differentiate between human users and automated bots. This is crucial in various online services because bots can often perform malicious activities, such as spamming, account creation, or scraping content. By requiring users to complete a challenge that would be easy for a human but difficult for a bot (like identifying distorted letters or selecting images that meet certain criteria), a CAPTCHA helps ensure that only legitimate users can access certain functionality on a website.

The other options address different concepts. While securing a website against cyber attacks is important, a CAPTCHA is just one of many security measures and primarily focuses on user verification rather than overall security measures for preventing attacks. Encrypting passwords is another important aspect of online security, which safeguards user data during transmission and storage, but this does not relate to user verification. Compressing data is a technique used to improve loading times and performance, particularly for websites or applications, but does not pertain to distinguishing between humans and bots. Thus, the central role of a CAPTCHA is specifically to identify and confirm that the user interacting with the system is indeed a human, making the answer clearly focused on user verification.