CAPTCHA is a kind of security used in various websites that provides challenge to users and its response that proves the user is a human being and not a robot. Full form of captcha is termed as Completely Automated Public Turing test. It is a type of security check to make humans and bots. It gives protection by completing a test which defends toward spam.
Captcha test is done by the user just by entering the image code in a text box given in a zigzag way. This image code can be in letter form or numbers. To prove you to be a human, the code given is to be typed in the text box. It is an intelligent way to remove bots from doing any activity on your page.
Captcha provides protection from bots at the remote server, ensuring only humans can use the computer. The captcha image is created by the computer, but it cannot be read by a computer as humans can.
There are a number of captchas alternatives available like image captcha, text captcha, puzzle, and audio captcha that can be used on the website to block spam done by hackers and prevent threats to your personal computer. Security check in the form of captcha helps to distinguish between humans and bots, to be safe a captcha must be added to your website to eliminate bot attacks. Users can get rid of fake registration of bots and can deal with human beings.
Honeypot is a trap for the bot. Alternative to captcha which requires proving that you are a human being can be removed. Here, a time-based alternative or honey pot can be used as a substitute.
The time-based alternative requires the user to fill a form, and if such form is filled before said duration then it would be termed as a bot activity as human efforts require some time to complete the form.
Honey pot solution works when a hidden field is placed in the form that a bot can identify but the human being cannot. If such a field is being filled then it would be a spambot activity as the user cannot see such fields.
It simply requires a user to slide left to right on the screen to prove it as a human activity. This tool works like that a tool is visible to the user, but remains hidden to spambot.
The Nocaptcha wants users to click on a checkbox saying that they are not robots. This is a simple method for users to follow, unlike others which require users to fill an image that has a distorted text. This method is very simple for users to use, just a click at the box as it uses artificial intelligence, and also Google verifies its highest rate of accuracy.
reCAPTCHA is the captcha alternative that can be used. It uses scanned audio and text that a bot cannot recognize. This method provides good security compared to the captcha method, which uses text-based images. It is not suitable for users who have audio and visual problems. But provides an alternative to use either audio or video captcha. Such a method is not suitable for people having audiovisual disabilities.
A CAPTCHA bot bypasses human tests to verify them as being human. These bots are being used on websites where there is heavy traffic and the manual test takes a lot of time and creates more traffic. Captcha bots are being designed to clear the captcha test of character string automatically and avoid the captcha test for humans.
These are the original methods by which humans were authenticated. It uses random letter, words combinations that can be in upper case, lower case or mixed. This text is provided in a distorted manner with different colored backgrounds, it can be in overlapping characters that requires interpretation by the user. This kind of text captcha provides good security from bots, and same text reading can be difficult for humans as well.
These CAPTCHAs use photos of animals or some site scenes. These CAPTCHAs ask users to match images with the image shown. This is comparatively easier to text based captchas. But this captcha is a limitation for visually impaired people. Image based captchas are more difficult for bots, requiring recognition of a matching image, than text based captchas.
Friends are connected through social media, friend recognition captcha is also one of the captcha alternatives seen. The latest captcha method to recognize a friend to authenticate that user is a human being and not a bot. Users are shown an image being taken from their social media profile and will be asked to name the person they see in the given image. This method has a con that a human being cannot remember the name of all his social media friends, and using an image from someone’s profile is also a matter of concern. This technique is not suitable for visually impaired humans.
This captcha asks the user to do a particular task while interacting with the user. Such activity includes sliding the cursor to the end of the page to complete the task or to move to a next level. It can also include dragging and dropping an object. This is an easier task for humans, but is difficult for bots to do this. It is again a limitation for people having a disability.
Which method would be the best captcha that can be used by websites to avoid bot attacks can be chosen by actually experimenting with various captcha alternatives to choose the best as per user experience and their feedback. Captcha on the websites reduces the risk of bot attacks. Still, companies need to develop new ways of making differentiation between bots and humans. Captcha solution works but is not an efficient way to mitigate the risk.