A ChatBot is a machine-learning based conversational dialogue engine built using Python which makes it possible to generate responses based on collections of known conversations. The language independent design of chatbot allows it to be trained to speak any language.
History of chatbots dates back to 1966 when a computer program called ELIZA was invented by Weizenbaum. It imitated the language of a psychotherapist from only 200 lines of code. You can still converse it here: Eliza
On similar lines let's create a very basic chatbot utlising the Python's NLTK library.It's a very simple bot with hardly any cognitive skills,but still a good way to get into NLP and get to know about chatbots.
An untrained instance of ChatterBot starts off with no knowledge of how to communicate. Each time a user enters a statement, the library saves the text that they entered and the text that the statement was in response to. As ChatterBot receives more input the number of responses that it can reply and the accuracy of each response in relation to the input statement increase. The program selects the closest matching response by searching for the closest matching known statement that matches the input, it then returns the most likely response to that statement based on how frequently each response is issued by the people the bot communicates with.