There are different approaches and tools that you can use to develop a chatbot. Depending on the use case you want to address, some chatbot technologies are more appropriate than others. In order to achieve the desired results, the combination of different AI forms such as natural language processing, machine learning and semantic understanding may be the best option.

Simply put, chatbots are computer programs designed to have conversations with human users. Chances are you’ve interacted with one. They answer questions, guide you through a purchase, provide technical support, and can even teach you a new language. You can find them on devices, websites, text messages, and messaging apps—in other words, they’re everywhere.
On the other hand, early adoption can be somewhat of a curse. In 2011, many companies and individuals, myself included, invested a lot of time and money into Google+, dubbed to be bigger than Facebook at the time. They acquired over 10 million new users within the first two weeks of launch and things were looking positive. Many companies doubled-down on growing a community within the platform, hopeful of using it as a new and growing acquisition channel, but things didn't exactly pan out that way.
ETL. The bot relies on information and knowledge extracted from the raw data by an ETL process in the backend. This data might be structured (SQL database), semi-structured (CRM system, FAQs), or unstructured (Word documents, PDFs, web logs). An ETL subsystem extracts the data on a fixed schedule. The content is transformed and enriched, then loaded into an intermediary data store, such as Cosmos DB or Azure Blob Storage.
A chatbot is a computer program that simulates human conversation through voice commands or text chats or both. Chatbot, short for chatterbot, is an Artificial Intelligence (AI) feature that can be embedded and used through any major messaging applications. There are a number of synonyms for chatbot, including "talkbot," "bot," "IM bot," "interactive agent" or "artificial conversation entity."
Feine, J., Morana, S., and Maedche, A. (2019). “Leveraging Machine-Executable Descriptive Knowledge in Design Science Research ‐ The Case of Designing Socially-Adaptive Chatbots”. In: Extending the Boundaries of Design Science Theory and Practice. Ed. by B. Tulu, S. Djamasbi, G. Leroy. Cham: Springer International Publishing, pp. 76–91. Download Publication

Social networking bots are sets of algorithms that take on the duties of repetitive sets of instructions in order to establish a service or connection among social networking users. Various designs of networking bots vary from chat bots, algorithms designed to converse with a human user, to social bots, algorithms designed to mimic human behaviors to converse with behavioral patterns similar to that of a human user. The history of social botting can be traced back to Alan Turing in the 1950s and his vision of designing sets of instructional code that passes the Turing test. From 1964 to 1966, ELIZA, a natural language processing computer program created by Joseph Weizenbaum, is an early indicator of artificial intelligence algorithms that inspired computer programmers to design tasked programs that can match behavior patterns to their sets of instruction. As a result, natural language processing has become an influencing factor to the development of artificial intelligence and social bots as innovative technological advancements are made alongside the progression of the mass spreading of information and thought on social media websites.

Today, consumers are more aware of technology than ever. While some marketers may be worried about overusing automation and chat tools because their tech-savvy audience might notice. Others are embracing the bots and using them to improve the user journey by providing a more personalized experience. Ironically, sometimes bots are the key to adding a human touch to your marketing communications.

Die meisten Chatbots greifen auf eine vorgefertigte Datenbank, die sog. Wissensdatenbank mit Antworten und Erkennungsmustern, zurück. Das Programm zerlegt die eingegebene Frage zuerst in Einzelteile und verarbeitet diese nach vorgegebenen Regeln. Dabei können Schreibweisen harmonisiert (Groß- und Kleinschreibung, Umlaute etc.), Satzzeichen interpretiert und Tippfehler ausgeglichen werden (Preprocessing). Im zweiten Schritt erfolgt dann die eigentliche Erkennung der Frage. Diese wird üblicherweise über Erkennungsmuster gelöst, manche Chatbots erlauben darüber hinaus die Verschachtelung verschiedener Mustererkennungen über sogenannte Makros. Wird eine zur Frage passende Antwort erkannt, kann diese noch angepasst werden (beispielsweise können skriptgesteuert berechnete Daten eingefügt werden – „In Ulm sind es heute 37 °C.“). Diesen Vorgang nennt man Postprocessing. Die daraus entstandene Antwort wird dann ausgegeben. Moderne kommerzielle Chatbot-Programme erlauben darüber hinaus den direkten Zugriff auf die gesamte Verarbeitung über eingebaute Skriptsprachen und Programmierschnittstellen.
You may remember Facebook’s big chatbot push in 2016 –  when they announced that they were opening up the Messenger platform to chatbots of all varieties. Every organization suddenly needed to get their hands on the technology. The idea of having conversational chatbot technology was enthralling, but behind all the glitz, glamour and tech sex appeal, was something a little bit less exciting. To quote Gizmodo writer, Darren Orf:
All of these conversational technologies employ natural-language-recognition capabilities to discern what the user is saying, and other sophisticated intelligence tools to determine what he or she truly needs to know. These technologies are beginning to use machine learning to learn from interactions and improve the resulting recommendations and responses.
The chatbot is trained to translate the input data into a desired output value. When given this data, it analyzes and forms context to point to the relevant data to react to spoken or written prompts. Looking into deep learning within AI, the machine discovers new patterns in the data without any prior information or training, then extracts and stores the pattern.
The chatbot uses keywords that users type in the chat line and guesses what they may be looking for. For example, if you own a restaurant that has vegan options on the menu, you might program the word “vegan” into the bot. Then when users type in that word, the return message will include vegan options from the menu or point out the menu section that features these dishes.
Do the nature of our services and size of our customer base warrant an investment in a more efficient and automated customer service response? How can we offer a more streamlined experience without (necessarily) increasing costly human resources?  Amtrak’s website receives over 375,000 daily visitors, and they wanted a solution that provided users with instant access to online self-service.
“They’re doing things we’re simply not doing in the U.S. Imagine if you were going to start a city from scratch. Rather than having to deal with all the infrastructure created 200 years ago, you could hit the ground running on the latest technology. That’s what China’s doing — they’re accessing markets for the first time through mobile apps and payments.” — Brian Buchwald, CEO of consumer intelligence firm Bomoda
Forrester Launches New Survey On AI Adoption There’s no doubt that artificial intelligence (AI) is top of mind for executives. AI adoption started in earnest in 2016, and Forrester anticipates AI investments to continue to increase. Leaders are quickly waking up to AI’s disruptive characteristics and the need to embrace this emerging technology to remain […]

“Beware though, bots have the illusion of simplicity on the front end but there are many hurdles to overcome to create a great experience. So much work to be done. Analytics, flow optimization, keeping up with ever changing platforms that have no standard. For deeper integrations and real commerce like Assist powers, you have error checking, integrations to APIs, routing and escalation to live human support, understanding NLP, no back buttons, no home button, etc etc. We have to unlearn everything we learned the past 20 years to create an amazing experience in this new browser.” — Shane Mac, CEO of Assist
Keep it conversational: Chatbots help make it easy for users to find the information they need. Users can ask questions in a conversational way, and the chatbots can help them refine their searches through their responses and follow-up questions. Having had substantial experience with personal assistants on their smartphones and elsewhere, users today expect this level of informal interaction. When chatbot users are happy, the organizations employing the chatbots benefit.
Since 2016 when Facebook allows businesses to deliver automated customer support, e-commerce guidance, content and interactive experiences through chatbots, a large variety of chatbots for Facebook Messenger platform were developed.[35] In 2016, Russia-based Tochka Bank launched the world's first Facebook bot for a range of financial services, in particularly including a possibility of making payments. [36] In July 2016, Barclays Africa also launched a Facebook chatbot, making it the first bank to do so in Africa. [37]