You must have been asked by a website to enter a unique code, or choose an image that matches the instructions, yes it’s a captcha, does captcha protect your website?. When you enter the wrong unique code you will be annoyed, don’t be upset, try to find out what it is and what it does?.
What is Captcha? Does Captcha Protect your Website?
Website users complain that there are many fake accounts that register and spam comments a lot. To solve this problem captcha technology was created in 2000. The effectiveness in that year reached 97%.
Based on what we see, a captcha is an image, number, or whatever that verifies us that we are not a robot. Captcha is indeed easy for humans to pass, but for robots to pass it is very difficult.
So, captcha is a technology to differentiate between robots and real users. The process is designed to be solved by humans and must be bypassed so that the user can access the desired site.
Type of Captcha
Recaptcha Google
There are several captcha services available on the internet. Well, one of the providers is Google, the feature is called Google reCaptcha. Secure tools from Google are considered very difficult for robots to penetrate, but very easy for humans to use. Because Google’s reCaptcha has a dataset and documentation that is divided into two versions, namely: Google reCaptcha v2 and Google reCaptcha v3. What distinguishes the two reCaptcha is the automatic feature of reCaptcha v3, Google reCaptcha v3 will perform an automatic scan of visitor activity. For example, scanning customer posts on a review page. If detected as bot activity, the system will immediately delete the post. While reChapta v2 is still manual. An example of a reCaptcha image is below.

Text Captcha
This captcha contains text and numbers or even a combination of both. This type requires the visitor to enter a series of numbers or letters that are displayed. This captcha makes it easier for website users who have visual impairments. However, this captcha has many loopholes for spambots to break into because of its simplicity. An example of TextCaptcha is below.

Picture Recognition captcha
This captcha requires visitors to select a predefined photo section before accessing a website page. For example, the system instructs visitors to select a section of the image of a traffic light as shown below.

The advantage of this system is that it makes it difficult for the robot to spam, but the disadvantage is that this system takes a lot of time to pass it. There are many types of captcha that we rarely know and rarely use, namely math captcha, 3d captcha, jQuery Slider captcha.