There are multiple chatbot development platforms available if you are looking to develop Facebook Messenger bot. While each has their own pros and cons, Dialogflow is one strong contender. Offering one of the best NLU (Natural Language Understanding) and context management, Dialogflow makes it very easy to create Facebook Messenger bot. In this tutorial, we’ll… 

Closed domain chatbots focus on a specific knowledge domain, and these bots may fail to answer questions in other knowledge domains. For example, a restaurant booking conversational bot will be able to take your reservation, but may not respond to a question about the price of an air ticket. A user could hypothetically attempt to take the conversation elsewhere, however, closed domain chatbots are not required, nor often programmed to handle such cases.

We then ran a second test with a very specific topic aimed at answering very specific questions that a small segment of their audience was interested in. There, the engagement was much higher (97% open rate, 52% click-through rate on average over the duration of the test). Interestingly, drop-off went wayyy down there. At the end of this test, only 0.29% of the users had unsubscribed.
I know what you’re thinking – when will the world of marketing just stand still for a moment and let us all catch up?!?! No such luck, dear readers. No sooner have we all gotten to grips with the fact that we’re going to have to start building live video campaigns into our content marketing strategies, something else comes along that promises to be the next game-changer. And so here we are with the most recent marketing phenomenon – chatbots.
Previous generations of chatbots were present on company websites, e.g. Ask Jenn from Alaska Airlines which debuted in 2008[20] or Expedia's virtual customer service agent which launched in 2011.[20] [21] The newer generation of chatbots includes IBM Watson-powered "Rocky", introduced in February 2017 by the New York City-based e-commerce company Rare Carat to provide information to prospective diamond buyers.[22] [23]

Developed to assist Nigerian students preparing for their secondary school exam, the University Tertiary Matriculation Examination (UTME), SimbiBot is a chatbot that uses past exam questions to help students prepare for a variety of subjects. It offers multiple choice quizzes to help students test their knowledge, shows them where they went wrong, and even offers tips and advice based on how well the student is progressing.
NanoRep is a customer service bot that guides customers throughout their entire journey. It handles any issues that may arise no matter if a customer wants to book a flight or track an order. NanoRep isn’t limited to predefined scripts, unlike many other customer service chatbots. And it delivers context-based answers. Its Contextual-Answers solution lets the chatbot provide real-time responses based on:
Interface designers have come to appreciate that humans' readiness to interpret computer output as genuinely conversational—even when it is actually based on rather simple pattern-matching—can be exploited for useful purposes. Most people prefer to engage with programs that are human-like, and this gives chatbot-style techniques a potentially useful role in interactive systems that need to elicit information from users, as long as that information is relatively straightforward and falls into predictable categories. Thus, for example, online help systems can usefully employ chatbot techniques to identify the area of help that users require, potentially providing a "friendlier" interface than a more formal search or menu system. This sort of usage holds the prospect of moving chatbot technology from Weizenbaum's "shelf ... reserved for curios" to that marked "genuinely useful computational methods".
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