Chatbots such as ELIZA and PARRY were early attempts at creating programs that could at least temporarily fool a real human being into thinking they were having a conversation with another person. PARRY's effectiveness was benchmarked in the early 1970s using a version of a Turing test; testers only made the correct identification of human vs. chatbot at a level consistent with making a random guess.
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.
Chatbots have been used in instant messaging (IM) applications and online interactive games for many years but have recently segued into business-to-consumer (B2C) and business-to-business (B2B) sales and services. Chatbots can be added to a buddy list or provide a single game player with an entity to interact with while awaiting other "live" players. If the bot is sophisticated enough to pass the Turing test, the person may not even know they are interacting with a computer program.

Niki is a personal assistant that has been developed in India to perform an impressively wide variety of tasks, including booking taxis, buses, hotels, movies and events, paying utilities and recharging your phone, and even organizing laundry pickup and delivery. The application has proven to be a huge success across India and won the Deep Tech prize at the 2017 AWS Mobility Awards.

If the success of WeChat in China is any sign, these utility bots are the future. Without ever leaving the messaging app, users can hail a taxi, video chat a friend, order food at a restaurant, and book their next vacation. In fact, WeChat has become so ingrained in society that a business would be considered obsolete without an integration. People who divide their time between China and the West complain that leaving this world behind is akin to stepping back in time.
Facebook Messenger chat bots are a way to communicate with the companies and services that you use directly through Messenger. The goal of chat bots is to minimize the time you would spend waiting on hold or sifting through automated phone menus. By using keywords and short phrases, you can get information and perform tasks all through the Messenger app. For example, you could use bots to purchase clothing, or check the weather by asking the bot questions. Bot selection is limited, but more are being added all the time. You can also interact with bots using the Facebook website.
Dialogflow is a very robust platform for developing chatbots. One of the strongest reasons of using Dialogflow is its powerful Natural Language Understanding (NLU). You can build highly interactive chatbot as NLP of Dialogflow excels in intent classification and entity detection. It also offers integration with many chat platforms like Google Assistant, Facebook Messenger, Telegram,…
In 2000 a chatbot built using this approach was in the news for passing the “Turing test”, built by John Denning and colleagues. It was built to emulate the replies of a 13 year old boy from Ukraine (broken English and all). I met with John in 2015 and he made no false pretenses about the internal workings of this automaton. It may have been “brute force” but it proved a point: parts of a conversation can be made to appear “natural” using a sufficiently large definition of patterns. It proved Alan Turing’s assertion, that this question of a machine fooling humans was “meaningless”.
Die Herausforderung bei der Programmierung eines Chatbots liegt in der sinnvollen Zusammenstellung der Erkennungen. Präzise Erkennungen für spezielle Fragen werden dabei ergänzt durch globale Erkennungen, die sich nur auf ein Wort beziehen und als Fallback dienen können (der Bot erkennt grob das Thema, aber nicht die genaue Frage). Manche Chatbot-Programme unterstützen die Entwicklung dabei über Priorisierungsränge, die einzelnen Antworten zuzuordnen sind. Zur Programmierung eines Chatbots werden meist Entwicklungsumgebungen verwendet, die es erlauben, Fragen zu kategorisieren, Antworten zu priorisieren und Erkennungen zu verwalten[5][6]. Dabei lassen manche auch die Gestaltung eines Gesprächskontexts zu, der auf Erkennungen und möglichen Folgeerkennungen basiert („Möchten Sie mehr darüber erfahren?“). Ist die Wissensbasis aufgebaut, wird der Bot in möglichst vielen Trainingsgesprächen mit Nutzern der Zielgruppe optimiert[7]. Fehlerhafte Erkennungen, Erkennungslücken und fehlende Antworten lassen sich so erkennen[8]. Meist bietet die Entwicklungsumgebung Analysewerkzeuge, um die Gesprächsprotokolle effizient auswerten zu können[9]. Ein guter Chatbot erreicht auf diese Weise eine mittlere Erkennungsrate von mehr als 70 % der Fragen. Er wird damit von den meisten Nutzern als unterhaltsamer Gegenpart akzeptiert.
This means our questions must fit with the programming they have been given.  Using our weather bot as an example once more, the question ‘Will it rain tomorrow’ could be answered easily. However if the programming is not there, the question ‘Will I need a brolly tomorrow’ may cause the chatbot to respond with a ‘I am sorry, I didn’t understand the question’ type response.
The term "ChatterBot" was originally coined by Michael Mauldin (creator of the first Verbot, Julia) in 1994 to describe these conversational programs.[2] Today, most chatbots are accessed via virtual assistants such as Google Assistant and Amazon Alexa, via messaging apps such as Facebook Messenger or WeChat, or via individual organizations' apps and websites.[3][4] Chatbots can be classified into usage categories such as conversational commerce (e-commerce via chat), analytics, communication, customer support, design, developer tools, education, entertainment, finance, food, games, health, HR, marketing, news, personal, productivity, shopping, social, sports, travel and utilities.[5]