Get to know what is a captcha, its types, and its function on a website

Before logging into a website, you may have been asked to enter a code in the form of an arrangement of letters or numbers. This is what is called a captcha. Simply put, captcha is a general security system that must be owned by website owners.

So as a user, do you know the actual function of the captcha? For more details, see the full explanation in the following article, come on!

What is a captcha?

The meaning of captcha is a security feature to ensure the website is accessed by humans, not robots. The term captcha comes from English which means to catch and was coined by Luis von Ahn, Manuel Blum, Nicholas J. Hopper (Carnegie Mellon University) and Jonn Langford (IBM) in the 2000s.

Captcha is an abbreviation of “Completely Automated Public Turing Test to Tell Computers and Human Aparts”. This term began to be used at Carnegie Mellon University in 2000 and continues to develop until now.

How captcha works

The way captcha works is by bringing up a form of verification challenge response (challenge response test) when using a computer to find out the answer is not generated by a computer, but a human.


process involves a server asking the user to complete a simple verification that the server can assess. Basically captcha is a technology as a differentiator between robots and humans and the verification process is designed so that it can only be completed by humans.

In this case you must be able to crack the code in order to access the site you want. Websites that apply captcha in it can avoid spam.

Examples of using captcha

The use of captcha is applied to various websites with the aim of verifying that every website user is not a robot.


example on the online test website. By using captcha, online test websites can prevent people from using robots during the test. That way only legitimate participants can take the online test.

Type of captcha


this modern era, many types of captcha code examples are used. For more details, the sample captcha code is as follows.

1. Recaptcha google

This type of captcha code is the easiest method for visitors to use. How google recaptcha works is by asking visitors to check a small dialog box that says “I am not a robot” without having to type anything.

This captcha code keeps track of while the user is carrying out an activity and identifies the activity when accessing the page whether it is human or robot.

Also read: Understanding Firewall, Functions, Benefits, How it Works and Types

2. Text captcha

Captcha text is a captcha code consisting of a combination of letters, numbers, or symbols that requires visitors to write down the code that appears. However, because of its simplicity, this captcha has a great chance of being hacked by spambots.


are several techniques that can be used to create captcha text, such as:

  • Gimpy: by using arbitrary words obtained from 850 words and displayed randomly, like being overwritten using another slightly transparent image.
  • EZ-Gimpy: is a variation of Gimpy that uses only one word.
  • Gimpy-r: uses random letters which then uses an irregular styling and then adds a confused image to the background.
  • Simards HIP: by using letters and numbers in an irregular manner and the layout is irregular, then patterns and colors are added.

3. 3D captcha

3D captcha is a slightly more difficult version of text captcha because the text displayed is a 3D image. This captcha code is more convincing with the level of difficulty.

4. Picture recognition captcha

Picture recognition captcha is an image-based captcha code and is a development of text captcha. Users are asked to recognize the listed images such as landscape images, photos, graphic elements and others.

In this case the image captcha code becomes a problem for the visually impaired, and bots will have a hard time bypassing the image-based captcha.

5. jQuery slider captcha

jQuery slider captcha is an example of captcha code which is easy to complete. You are required to move the small box from left to right to verify the captcha code. The variations of this captcha slide can be in the form of a puzzle.

id="6-math-captcha">6. Math captcha

This captcha mechanism uses simple mathematical problems such as adding or subtracting “2+3 or 3-1” so that it will be difficult for the robot to answer correctly. There is also a form of command to complete the missing word in a sentence.

Captcha function

You already know what a captcha is. But that’s not enough if you don’t know what the actual captcha function is. Captcha has a very important function for a website because it is considered a verification feature so that the system is not easily entered by robots.

The main function of the captcha code is for the website to reject when the robot will enter the website. For more details, here is the function of the captcha.

1. Prevent fake account registration

Free services provided by companies like Microsoft, Google, and others require a captcha which will serve as protection against misuse of data by various automated scripts.

That’s why when registering, you often find captcha. For information, there has been a bot attack when there were registrations of thousands of email accounts at the same time, you know, friend! Therefore the captcha is there so that it doesn’t happen again.

2. Protect email addresses from scrapers

Scraper is a robot that is able to cut a person’s email address from a website, after which it takes over access to it. The function of captcha is to protect and hide your email address from scraper robots so that spammers can’t spread spam and find your email.

3. Prevent search engine bots

With the captcha, it can provide protection on a website page from search engine bots which occasionally appears to read pages on those websites.

Indeed, there are tags that can prevent bots on search engines. But this is sometimes less effective as a barrier search engine bots. Therefore, captcha is used to ensure the security of website pages.

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4. Securing online buying and selling transactions on the website

The application of captcha in online stores is very important, because this will affect rating on your online store, namely by making sure an order for goods on your online store site is a human and not a robot.

If there is a fake purchase, the consequences can be fatal, friend. customer experience your online store will be bad so that it can affect sales performance. It is feared that there will be no reordering by customers and the reputation of the online store that you have built will fall.

5. Prevent spam comments on blogs or websites

Most bloggers use fake comments to increase the rating on their sites so that they immediately enter the initial search on search engines. With the captcha, it will prevent spam in the comments column, because every time you post a comment, the user is required to enter the available captcha.

How to install captcha on website

To install captcha on the website, you must have experience in the IT field in the form of HTML knowledge. But if you have a team of website developers, they will do it easily and quickly.

Now Google offers reCaptcha which can be used on your website. First of all you need to register your domain first. After that, here are the steps to consider:

  1. Create a Google or Gmail account, if you already have it, you can directly login.
  2. Access the Google reCaptcha website, then click Admin Console.
  3. Register your new domain with Google reCaptcha.
  4. Choose the types of captcha according to the needs of your website.
  5. Fill in your website domain information and email. Don’t forget to check the Terms of Service. Then click submit.
  6. Copy the site key and secret key.
  7. After that, do the Captcha integration with the website you have.

Now, you already know right how useful captcha code to secure a website. Eits but actually, there are still many ways you can do to prevent crime on online sites. Anything? Check out the full details in other Jagoan Hosting reviews right now, friend!

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