What is Captcha?

Captcha is a feature that provides a layer of security on the website to ensure that the website is accessed by real humans, not robots.
What is Captcha

The function of captcha is to avoid spam, because nowadays automation technology is increasingly sophisticated and is often used by cyber criminals for bad purposes. An example of a captcha is when you open a website, you are asked to fill in a series of letters, pictures, or picture puzzles first.

Although you may have felt annoyed when the code entered was always wrong when you had to rush to open a website, actually all of this is useful for the good of all parties. Without this method, your favorite website or blog might crash. Wow, how could that be?

Well, through this article, we will discuss what a captcha is, its function on a website, and the types that are currently available.

Understanding Captcha

Basically, CAPTCHA stands for Completely Automated Public Turing Test to Tell Computers and Humans A part . From this English term, it can be concluded that the meaning of captcha is an automatic process carried out to distinguish whether a website visitor is a human or a robot (Computers and Humans Apart). 

The most common example is when you need to click “I am not a Robot” or “I am human” when opening a website.

illustration of what is captcha

Access authentication is in the form of validation with a special design, which ensures that visitors who access the website are not robots. Therefore, authentication questions are always designed in such a way that only real humans can solve them.

Sometimes, filling out this code is a little time consuming. However, the actual captcha function is no joke, especially for website owners.

It is undeniable, spam today is very much and is everywhere. Well, to avoid that, a captcha was created to help add a layer of security.

Captcha Function for Website

After discussing what captcha is and what it means, next we will discuss its uses.

The existence of this authentication method is very beneficial for website owners because it can increase website security. In fact, you could say its function is very crucial so that the site system is not easily broken into by robots.

Here are the benefits of Captcha for websites:

1. Prevent Spam Comments

Have you ever been asked to enter a captcha from a combination of numbers, letters, or images first when you wanted to write a comment on a blog or website? Well, this is implemented to prevent spam comments on websites or blogs.

For those of you who have a website or blog, you must have often encountered spam comments in the form of product promotions or those that are not related to the topic of the article. Of course, this will greatly damage the reputation of your site or blog, and can even make visitors feel uncomfortable.

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Generally, these spam comments are sent to increase the blog's rating suddenly. However, Google's algorithm considers spam comments a problem, which will actually cause your website or blog to be removed from Google search results.

Well, you as a website or blog owner need to take advantage of it so that your Search Engine Optimization efforts are not disturbed.

2. Blocking Dictionary Attack on Websites or Blogs

Quoted from Wikipedia , a dictionary attack is an attack to break into a security system by cracking the code in the cipher or authentication mechanism, using words or phrases contained in the dictionary thousands or even millions of times.

Dictionary attacks on this website or blog can lead to account theft cases, you know. With the captcha, you can prevent this type of attack.

Its use will protect the website or blog further, making it more secure and avoiding theft that comes from abuse by irresponsible persons.

3. Avoiding Fake Account Registration

Currently, many platforms provide free registration services for website users. For example, Google and YouTube, both implement captcha to prevent misuse of data by automated scripts (bots/robots). Well, the function here is to avoid creating fake accounts, which can result in data theft on the website.

The registration form of this fake account should not be underestimated because it can make the database full, and ultimately affect the effectiveness of the email. If you have a website that sends emails automatically, for example for newsletters or email marketing , these fake accounts will not receive the email in your inbox. As a result, your email reputation can be compromised.

Email providers such as Gmail, Yahoo, and Outlook will judge your email reputation badly because many marketing emails are not sent. If this is the case, the email provider will direct the marketing emails you send to the spam folder so that this digital marketing strategy becomes ineffective because it is not on target.

4. Securing Online Transactions on the Website

It is very important to apply captcha on online store websites. Because, this will affect the reputation of your online store, which is to ensure that the product buyer on your site is a real human, and not a robot.

If a fake purchase occurs, the product in your online storefront website will appear to be sold, but the buyer is not a real party.

The result can be quite fatal. The customer experience in your online store will get worse, affecting sales. I'm afraid, here, there will be no repeat orders from customers, or cool brand names that you have built in such a way that they just fall.

5. Protect Email Addresses from Scrapers

Scraper is one of the security threats that compromises email, in the form of bots that can 'steal' and export email addresses from a website, and can lead to access takeover.

The captcha here will serve to protect and hide your email address from scrapers so that spammers can't carelessly spread spam and look for your email address.

Types of Captcha

Captcha has various types that website owners can choose to implement security authentication. Modern Captcha itself is actually divided into three types, namely basic text, images, and audio.

Types of Captcha

The following captcha can be installed by website owners:


Captcha text is the most frequently encountered and commonly used. In addition, this type is the first to be used since the existence of captcha to distinguish between humans and robots. 

Usually, a text captcha consists of a combination of numbers, letters, or symbols. Visitors will be asked to fill in the code of these characters whose order is displayed randomly.

There are several ways to create a text captcha, including:

Gimpy — Words from the dictionary that change irregularly, are overwritten using another slightly transparent image.

EZ-Gimpy — A variation of gimpy, but uses only one word.

gimpy-r — The letters are arranged randomly, plus a background image so that it looks a bit confusing.

Simard's HIP — Letters and numbers are randomized and irregular, added color hues.

This type is easy to use for site visitors who have visual impairments, because it is still easy to identify.

However, because it is easy to solve, the result is still very possible for robots or spam to break into it.

2. Picture Recognition Captcha

This type of captcha uses an image for the authentication process. Image captcha is a developed version of the text type, and it is intended to replace captcha text. For this type of picture recognition, visitors must select a predetermined part of the photo, usually with instructions to click on the appropriate photo.

The images displayed also vary, usually in the form of graphic elements, scenery, traffic signs, and so on. Picture recognition captcha is a bit of a problem for website visitors who have visual impairments because they have to be really careful to see it.

The advantage is, this type is difficult to break into because spambots do not yet have the ability to recognize images.

3. Audio Captcha

Audio captcha is used as an alternative for website visitors who have visual impairments or are blind. As the name implies, this breed uses voice to dictate the code that needs to be written for authentication.

Audio captcha is also sometimes automatically included in the text captcha, with the speaker icon clickable to read out the code on the screen.

4. Math Captcha

Math captcha requires visitors to solve math problems. Of course, the problems that are done are also just simple mathematical calculations. Usually, the questions given are adding or subtracting two numbers. Visitors are asked to input the results of the calculation of the questions before logging in or submitting the process to the website.

This captcha that displays math problems makes it difficult for bots to answer the questions correctly because it is difficult to identify the questions. So, it is very unlikely for spambots to be able to break into this layer of security.

5. jQuery Slider Captcha

jQuery Slider Captcha is an authentication method that takes the form of a slider, requiring website visitors to swipe an element on the screen using the mouse to complete it. Usually, users just need to swipe the box from left to right to verify security.

This type is in the form of a puzzle that must be shifted to fit in the correct area, or there is also a command to move certain elements.

6. ReCaptcha

ReCaptcha is the easiest for site visitors. The way it works only requires us to check the words "I'm not a robot". Even so, this type of captcha is the most difficult for spambots to break.

Google's ReCaptcha has a dataset and documentation that is divided into two, namely: 

Google ReCaptcha v2 . This method displays the “I'm not a robot” checkbox on the website. Visitors simply check this box for the security verification process.

Google ReCaptcha V3. It's simpler than reCaptcha v2, and provides automatic security verification. The way it works is by scanning (scanning) visitor activity. If detected as bot activity, the captcha will delete the post. So, you as a website owner will also avoid spam comments.


Finished! In this article, you have learned about what captcha is, what it means, its function, and its types. After reading our guide, I hope you as a visitor and website owner are no longer confused and upset when you encounter captcha.

Although sometimes a little annoying, captcha has a very important role for the security of a website or blog. The uses of captcha include preventing fake account registration, spam, dictionary attacks, email theft, and securing online transactions.

You as a website or blog owner are strongly advised to install it, which is available in various types. Some of the commonly used captcha types are:

  • Captcha text
  • Picture Recognition Captcha
  • Audio Captcha
  • Math Captcha
  • jQuery Slider Captcha
  • ReCaptcha

You are free to choose which type to install according to the needs of your website or blog.

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