Image-based CAPTCHA usually provides users with images of objects, animals, people, or landscapes, instead of distorted text, to distinguish a human from a computer program. To increase the difficulty, there is mathematical CAPTCHA, which involves a basic math problem with easy-to-read numbers, and 3D CAPTCHA, which displays the characters with 3D effect. Simply showing the characters are not that difficult for bots. To pass the test and prove your human identity, simply type the characters you see in the image into the text box.

The most common types of CAPTCHA are:Ī text-based CAPTCHA test is made up of two parts: a randomly generated sequence of letters and/or numbers that appear as a distorted image, and a text box for input.

It works because a human looking at a distorted picture can read the words without any challenge, while a scraping tool doesn’t recognize them easily.Įven the most sophisticated automated system, which has been programmed to scan a picture of printed text and read the words, would still find it difficult to identify the words when they are too much distorted.ĬAPTCHA comes in several sizes and of different types. It usually shows a distorted string of random characters or numbers. The goal of CAPTCHA is to ask questions or make challenges that computers are unable to deal with. It is used to test whether a machine can think like humans. It is commonly used across the internet, particularly when purchasing products online or logging into a website.ĬAPTCHA technology is based on the Turing Test. This is a way to detect malicious robot behaviors, block the robot and protect the website from harm. How to Deal With CAPTCHA for Web ScrapingĪccording to Wikipedia, CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a type of challenge-response test used in computing to determine whether or not the user is human.

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