Tay was built to learn the way millennials converse on Twitter, with the aim of being able to hold a conversation on the platform. In Microsoft’s words: “Tay has been built by mining relevant public data and by using AI and editorial developed by a staff including improvisational comedians. Public data that’s been anonymised is Tay’s primary data source. That data has been modelled, cleaned and filtered by the team developing Tay.”
When one dialog invokes another, the Bot Builder adds the new dialog to the top of the dialog stack. The dialog that is on top of the stack is in control of the conversation. Every new message sent by the user will be subject to processing by that dialog until it either closes or redirects to another dialog. When a dialog closes, it's removed from the stack, and the previous dialog in the stack assumes control of the conversation.
With the AI future closer to becoming a reality, companies need to begin preparing to join that reality—or risk getting left behind. Bots are a small, manageable first step toward becoming an intelligent enterprise that can make better decisions more quickly, operate more efficiently, and create the experiences that keep customers and employees engaged.
This machine learning algorithm, known as neural networks, consists of different layers for analyzing and learning data. Inspired by the human brain, each layer is consists of its own artificial neurons that are interconnected and responsive to one another. Each connection is weighted by previous learning patterns or events and with each input of data, more "learning" takes place.

However, if you’re trying to develop a sophisticated bot that can understand more than a couple of basic commands, you’re heading down a potentially complicated path. More elaborately coded bots respond to various forms of user questions and responses. The bots have typically been “trained” on databases of thousands of words, queries, or sentences so that they can learn to detect lexical similarity. A good e-commerce bot “knows” that trousers are a kind of pants (if you are in the US), though this is beyond the comprehension of a simple, untrained bot.

A chatbot (also known as a spy, conversational bot, chatterbot, interactive agent, conversational interface, Conversational AI, talkbot or artificial spy entity) is a computer program or an artificial intelligence which conducts a conversation via auditory or textual methods.[1] Such programs are often designed to convincingly simulate how a human would behave as a conversational partner, thereby passing the Turing test. Chatbots are typically used in dialog systems for various practical purposes including customer service or information acquisition. Some chatbots use sophisticated natural language processing systems, but many simpler ones scan for keywords within the input, then pull a reply with the most matching keywords, or the most similar wording pattern, from a database.