How can I program a simple chat bot AI?

Question

I want to build a bot that asks someone a few simple questions and branches based on the answer. I realize parsing meaning from the human responses will be challenging, but how

Answer 1

I'm not sure this is what you're looking for, but there's an old program called ELIZA which could hold a conversation by taking what you said and spitting it back at you after performing some simple textual transformations.

If I remember correctly, many people were convinced that they were "talking" to a real person and had long elaborate conversations with it.