I am sure a lot of you have tried Eliza - the chatbot. You'd type something and get a pre-programmed response. It was fun.
The guy who wrote this in 1988 had thousands of conversations with it, and since going online in 1997, it has had over 20 million conversations. That's probably more conversations that the most fascinating human being you know. So when you are talking to it - it is getting a response based on a conversation it has had before.
It can be very silly sometimes, but the idea is fascinating.
As per WikiPedia
Cleverbot differs from traditional chatterbots in that the user is not holding a conversation with a bot that directly responds to entered text. Instead, when the user enters text, the algorithm selects previously entered phrases from its database of prior conversations. It has been claimed that "talking to Cleverbot is a little like talking with the collective community of the internet"
