aTCHA

A Captcha, short for Completely Automated Public Turing test to tell Computers and Humans Apart, is a program that can determine whether the user is a human or a computer. This is typically achieved through a challenge-response test, which requires the user to complete a task that is difficult for computers to do but easy for humans.

A Captcha often takes the form of a visual or audio challenge, such as identifying objects in an image or solving a mathematical problem. When a user attempts to access a website or service, they may be presented with a Captcha challenge that they must complete in order to proceed.

The purpose of a Captcha is to prevent automated programs, such as bots and spiders, from accessing a website or engaging in other online activities without the permission of the site owner. In this way, Captchas help to protect websites from spam and other forms of malicious activity.

Captchas are typically implemented as a security measure to prevent automated attacks, but they are not a foolproof measure. Computers are continually improving, and some modern Captchas have been shown to be vulnerable to hacking. Additionally, some users experience difficulties with Captchas due to issues with vision or hearing impairments, or due to language barriers.

Despite these limitations, Captchas remain a widely used security measure on the internet, and are often implemented in conjunction with other security measures, such as two-factor authentication and password protection, to provide an additional layer of security for online services.