Like them or not, CAPTCHAs have become ubiquitous on the Internet. What is CAPTCHA anyway, and where did it come from? Basically, CAPTCHA stands for Completely Automated Public Turing test to tell Computer and Humans Apart.
Responsible for eye-strain the world over, the humble CAPTCHAs have been the most powerful weapon in the fight against web spam. But how effective are they?
Since they were first used in 2000 by AltaVista and Yahoo, CAPTCHAs have done a great job at preventing bots and URL submissions from overrunning sites with spam, fraudulent registrations, fake sweepstakes entries, and other nefarious things.
Yet, CAPTCHAs still present a very controversial topic: you can’t do without them as a webmaster and you can’t stand them as a user.
Some CAPTCHAs are just impossible to figure – no matter who you are (a robot or a human), you won’t pass the test. The example below demonstrates an impossible-to-solve CAPTCHA:
Luckily, though, captures have clearly evolved over time, and not all CAPTCHAs are too difficult to solve nowadays. That's at least what one can notice from most modern-day CAPTCHAs, such as Google's text-based CAPTCHAs & the Re-CAPTCHA Project that is based on asking the user to recognize the words of older books. The idea is that those words are normally very hard to recognize by computers, but they can be trivially easy for humanbeings.
However, if the computer had trouble recognising the word in the first place, how can it tell if what you wrote in is nonsense? Simple – present the user with TWO words – one of which is known. The system assumes that if the user correctly types the known word, then the chances are that the unrecognizable word is also correct.
Another ingenious idea for one effective, yet more human-friendly CAPTCHA is one that presents images that are fairly difficult to process for computers semantically. Think about a group of pictures. Programming a computer to recognize a flower, for example, is hard enough, and to distinguish a cat from all the other animals and objects in the world is pretty much impossible at this point in time.
One can now say that despite all the odds, CAPTCHAs have evolved to be more fun, and fairly easier for real humans than they used to be. Thus, they have become more welcome than ever. Of course, it would be great if we didn't have to jump through hoops to submit a simple registration or entry form, but those hoops are actually there for our protection.
Although CAPTCHAs are not impenetrable to hacking or spamming, the chances of those spammers accomplishing the actual task of cracking the CAPTCHA often do not exceed 43% at their best. So, even if crackers succeeded in breaking one CAPTCHA or two, or dozens of them, the unpredictable randomness and complication of CAPTCHAs can always reduce the risk of those attempts and do its main task of protecting servers from bots and web spam. This is exactly what makes CAPTCHAs a necessity in our digital age.
Voila Social Media Team