A year or two ago I saw a television program about one of the men who invented "captcha" codes. This guy is the oober intelligent type that can ponder over the meaning of the universe for hours at a time, unlike me, who gets distracted by my own inner chatter after just a few seconds of pondering. The program footage showed him sitting in his office alone in the dark just pondering and thinking about how to solve different problems. One of the problems he pondered was how to make use of the man hours that are put in to surfing the internet. Consequently, the captcha codes were invented.
Remember, I'm not the oober intelligent one, so you are getting the sesame street interpretation of what I learned, but here is how I understand captchas. Basically, the computer can recognize text that we type. It can recognize many different fonts. But it still can't recognize some. When a person is required to type in a captcha code, they are teaching the computer how to recognize that font. Pretty clever, isn't it? So without having to hire anyone, they are able to complete a huge task! It only takes a few seconds (or longer, depending on the stinking difficult font that is used) for someone to type in the code. If they paid someone to sit down and do this, it would take years. But because there are so many people using the internet, a few seconds of their time solves the problem for free.
Another aspect of captchas is that because the computer can't read them, programmers can't send out spam comments on blogs. These are generated by a computer, and if the computer can't read the captcha code, the comment can't be published. This is a great security feature.
Now here comes the problem that they may not have been able to foresee. I don't know if you have noticed, but captcha codes are becoming increasingly difficult to read. I guess the computers can read the easy ones, so they are branching out to more difficult ones. But what do we do when the human can't read it well enough to translate it? And what do we do when the computer finally is able to read all of the fonts? Then how do we control the security? I'm thinking this system has a limit in the near future. But I'm sure the inventors are already working on this problem.
I know some people hate captcha codes, and in some cases refuse to use them. But I kind of like the work that is going on behind the scenes, so I'm willing to muddle through. And as a blogger, I continue to use them because I really don't like the sleezy comments I get from "robot" programs. So next time my captcha codes irritate you, just remember that I'm taking part in a great computer work, and helping to advance technology. :)