What is CAPTCHA?

 CAPTCHA  means Completely Automated Public Turing Test to Tell Computers and Human Apart). A technique used by a computer to tell if it is interacting with a human or another computer.

A CAPTCHA is a type of test that websites may force you to solve before they allow you access to things like forms or searches .You have seen  CAPTCHA test on lots of websites. The most common form of CAPTCHA is an image of several distorted  letters. 

CAPTCHA technology has its foundation in an experiment called the Turing Test. A Turing Test is a method of enquiry in Artificial Intelligence (AI) for determining whether or not a computer. Turing test developed by British Innovator Alan Turing.

CAPTCHA played an important role because they are designed to block activities from automated bots. In some websites, CAPTCHA's are programmed to popup in certain places, and they automatically fail or pass users.

Where we Found CAPTCHA?

On a web page or website when we want to enter our personal details ie credit card, debit card detail , we might be asked to copy a series of words including alphabet (either in Capital or Small letter) and numbers. Mostly it is a quick stop before we continue or activity. At  that time most  people though what a CAPTCHA is and what is its purpose?.

Purpose of CAPTCHA

Now a days with the advancement of technology, protection against hackers, SPAM and improving the security of the web pages. 

The CAPTCHA  which is used in the web pages asks the user to verify the CAPTCHA letters or image which include alphabet or numbers. Here the letters are not in serial manner or distorted. So the activist or bots are not able to find an incorrect way. So BOTs were unable to pass the CAPTCHA test. 

How to Keep CAPTCHA Code Secure

If your website needs proper protection from scammers, it's recommended to use a CAPTCHA. 

Secure Images: Images should be distorted randomly when presented to the user. 

Script Security: In addition to making sure your images are unreadable by computers, you should also ensure that there are no easy ways around the script level.

Unique CAPTCHAs: If every site used similar CAPTCHA codes, hackers could reach on and create bots that would bypass this test. That's why it is important to change the type of CAPTCHAs every so often and avoid common mathematical equations such as 1+1.

How CAPTCHA Prevents Scammers

CAPTCHA  has a variety of applications for keeping websites and users secure.

• Protects online polling
• Protect website registrations
• Protecting email address from scammers
• Protects dictionary attacks
• Preventing false comments

Different Types of CAPTCHA

• Text-based CAPTCHAs

Text-based CAPTCHAs are the original way in which humans were verified. These CAPTCHAs can use known words or phrases, or random combinations of digits and letters. It can also involve overlapping characters with graphic elements such as color, background noise, lines, arcs or dots. Which can also be complicated by geometric shapes that make it more difficult to overcome this security.

• CAPTCHA Image

Showing a series of images in some cases we have to identify the buses, photos of animals, shapes or scenes. Typically image based CAPTCHAs require users to select images matching a theme or to identify images that don't fit .Image - based CAPTCHAs are typically easier for humans to interpret than text-based.

  

•  Audio CAPTCHA

Audio CAPTCHAs were developed as an alternative that grants accessibility to visually impaired users. These CAPTCHAs are often used in combination with text or image-based CAPTCHAs. Audio CAPTCHAs present an audio recording of a series of letters or numbers which a user then enters.

• No CAPTCHA ReCAPTCHA

This type of CAPTCHA, known for its use by Google, is much easier for users than most other types. It provides a checkbox "I am not a robot" which users need to select and that's all. It works by tracking user movements and identifying if the click and other user activity on the page resembles human activity or bot.