A captcha (Completely Automated Public Turing test to tell Computers and Humans Apart) is a type of verification test designed to distinguish between a human user and a computer programme. A captcha usually consists of an image or task that only a human can solve. It is used to protect websites from bot attacks or other forms of automated vandalism.
Captcha can be found on many websites, such as social networking sites, account creation sites, online shop sites and many others. They are mainly used to protect systems from unauthorised access. Captchas are also often used to confirm user identities, stop spam and protect systems from DDOS attacks.
A captcha looks like a standard image or task that requires the user to enter an answer. The user must enter the answer to gain access to a specific site. If the answer is correct, the site will display correctly. If the answer is incorrect, the site may block access to the site or force the user to re-enter the answer.
Captcha can take a variety of forms, including:
– Picture with sound – in this case, the user must play a sound code and enter it into the text box.
– Maths task – the user must solve a simple maths task and enter the answer in the text box.
– Image selection – the user must select specific images from a list of displayed images.
– Word typing – the user must type a word or words into the text box.
– Checking a box – the user must select a box to confirm that they are human.
– Image and sound combination – the user must play a sound and select an image that matches the sound.
– ReCAPTCHA – this is a technology developed by Google that requires the user to enter multiple words from an image.
Captcha is used as a method to prevent unauthorised access to websites. This prevents hacking attacks, spam and other forms of unauthorised access. Captcha is also used to confirm