CAPTCHA is the Completely Automated Public Turing Test to Tell Computers and Humans Apart. You can use CAPTCHAs to differentiate between real users and automated users, such as bots.
What are CAPTCHAs Used for
CAPTCHAs are used by any website that wishes to restrict usage by bots.
- Maintaining poll accuracy
- Preventing Fake Registrations
- Preventing spam comments
- Preventing ticket inflation
- Making Online Shopping More Secure
- Protecting Email Accounts
- CAPTCHAs work by providing information to a user for interpretation. Traditional CAPTCHAs provide distorted or overlapping letters and numbers that a user must submit via a form field. The distortion of the letters made it difficult for bots to interpret the text and prevented access until the characters were verified.
- Since CAPTCHA was introduced, bots that use machine learning have been developed. These bots are better able to identify traditional CAPTCHAs with algorithms trained in pattern recognition. Due to this development, newer CAPTCHA methods are based on more complex tests. For example, reCAPTCHA requires clicking in a specific area and waiting until a timer runs out.
- Text-based
- Recaptcha
- 3D Captcha
- Mathematical Captcha
- Image-based captcha
Drawbacks of Using CAPTCHA
- Disruptive and frustrating for users
- May be difficult to understand or use for some audiences
- Some CAPTCHA types do not support all browsers
- Some CAPTCHA types are not accessible to users who view a website using screen readers or assistive devices
