On the Internet, nobody knows you're a dog.

This is the text of a famous cartoon by Peter Steiner that I reproduced below. This picture marked a turning point in the use of identity on the Internet, when it was realized that you don't have to tell the truth about yourself. The joke in the cartoon pushes it to the limit, as if you do not even have to be human. But is there anything else than humans on the Internet?

Actually yes. The Internet is full of robots or web bots. Those robots are not pieces of metal like Robby the robot. Instead, they are computer scripts that issue network requests and process the response without human intervention. How much of the world traffic those web bots represent is hard to estimate, but sources cited on Wikipedia mention that the vast majority of email is spam (usually sent by spambots), so it might be that humans issue a minority of requests on the Internet.

In my previous post I mentioned that computers do not understand humans. For the same reasons, it is sometimes difficult for a server to determine whether it is processing a request...