Definition
Completely Automated Public Turing test to tell Computers and Human Apart (CAPTCHA) is a security measure that authenticates that a user is not a robot. It prompts a user to complete or solve an easy task that would otherwise be challenging for a bot.
How CAPTCHA Works
- A user visits a site that uses CAPTCHA to verify human access.
- The website prompts a challenge, for example, a distorted text, image, or a puzzle.
- The user completes the task, proving to the system that they are indeed human and not a bot.
- The website checks the user’s response; if it’s correct, the user is granted access to the site. If not, the site prompts the user to try again.
- If the user cannot solve the CAPTCHA after several tries, they are locked out of the site.
Types of CAPTCHA
- Image-based CAPTCHA: This type of CAPTCHA presents the user with an image containing blurred text and then requests the user to type the correct name.
- Audio-based CAPTCHA: Audio-based CAPTCHAs are used when users cannot view or understand image-based CAPTCHAs.
- Game-based CAPTCHA: These CAPTCHAs ask users to solve a puzzle before they are allowed to access the site.
- Checkbox CAPTCHA: The user must tick a checkbox to prove that they are not a robot. They may also be required to answer additional questions or solve some puzzles to ensure that they are human.
- ReCAPTCHA: Google developed this type of CAPTCHA, which works with image and text recognition. It requires users to identify objects in an image or type in characters of distorted text.
- Mathematical CAPTCHA: This type of CAPTCHA requires the user to solve a basic arithmetic problem to be allowed access.
Advantages and Disadvantages of CAPTCHA
Pros
- Prevents fake registrations: CAPTCHA prevents bots from creating accounts that spread spam and malware.
- Guards against suspicious transactions: Companies use CAPTCHAs to prevent bots from initiating automated purchases.
- Protects online poll integrity: CAPTCHAs maintain poll integrity by preventing bots from voting.
- Stop service or product review spam: Websites using CAPTCHA prevent bots from submitting fake reviews meant to boost product or service ranking artificially.
- Prevent brute-force attacks: Prevent hackers from breaking into users’ accounts by asking them to complete a CAPTCHA.
Cons
- Inconvenient user experiences: CAPTCHA challenges are perceived by most users as being overwhelming and annoying.
- Accessibility challenges: Some CAPTCHA tasks, such as image-based CAPTCHAs, are challenging to solve for specific groups of people, such as visually impaired users.
- Privacy concerns: There are concerns about CAPTCHAs being invasive especially those that collect tracking data.