Captcha was invented back in 2000, and since then it has become an integral part of the Internet. Users encounter it when they try to register somewhere, leave a comment, or simply when there is increased activity. How to fill in the captcha correctly, and can you do without it?
The word "captcha" itself is a Russified version of the English abbreviation CAPTCHA (Completely Automatic Public Turing Test to Tell Computers and Humans Apart - a fully automatic Turing test for distinguishing between computers and people). It is a popular tool for distinguishing between humans and robots that are trying to perform certain actions on websites.
It is thanks to captcha that social networks are now not cluttered with an army of bots.
What is captcha for?
The main purpose of captcha is to protect against bots. Inanimate website visitors can contribute to cheating during voting, litter with comments with insults or advertisements, register hundreds of new bot users - captcha input helps protect against all this. It is assumed that the robot will not be able to capture, but for a living person it will not be difficult, and thus the captcha will save the site from the invasion of bots.
In file-sharing services, captchas are forced to enter so that you cannot add a link to the download program, but did everything manually (and accordingly saw all the ads).
If you show excessive activity on the site (for example, leaving too many comments on social networks), you may also be forced to enter a captcha to prove that you are not a robot.
How to enter captcha
The most popular captcha option is distorted letters, numbers, or their combinations, which must be correctly identified and entered. Some sites offer more interesting options. These can be simple math problems or simple questions, for example, "4 + 6 =" or "the capital of Russia".
There are captcha options, in which you need to arrange pictures vertically, several pictures, or just put a tick. There are also exotic options. Somewhere it is required to solve a problem from higher mathematics, somewhere to demonstrate knowledge of the Arabic language. Fortunately, these are not common occurrences.
For people with visual impairments, there is an audiocap that suggests identifying the code by ear.
Automatic captcha recognition
Of course, craftsmen have come up with many ways to bypass captcha. Bots can determine the correct combination of code from the information contained in the code of a web page, find the correct answer by simply iterating over the options.
A more difficult way is to use automatic text recognition programs. For example, computer scientists have learned to recognize captcha using the popular FineReader program.
There are also services for paid recognition of distorted text. But it is unlikely that you can make a lot on captcha. 1000 correctly recognized images cost no more than 20 rubles.
Pros and cons of captcha
This method of defense has many opponents. The criticism is mainly related to the inconvenience to the user. Few people like to poke around in illegible characters, which often have to be entered at random. And this does not contribute to good eyesight.
On the other hand, nothing better in terms of ease of use and quality has yet been invented. As soon as this happens, captcha will go down in history, because no one will use such inconvenient services unless absolutely necessary.
