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. 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.  In July 2016, Barclays Africa also launched a Facebook chatbot, making it the first bank to do so in Africa. 
This is a lot less complicated than it appears. Given a set of sentences, each belonging to a class, and a new input sentence, we can count the occurrence of each word in each class, account for its commonality and assign each class a score. Factoring for commonality is important: matching the word “it” is considerably less meaningful than a match for the word “cheese”. The class with the highest score is the one most likely to belong to the input sentence. This is a slight oversimplification as words need to be reduced to their stems, but you get the basic idea.
Kik Messenger, which has 275 million registered users, recently announced a bot store. This includes one bot to send people Vine videos and another for getting makeup suggestions from Sephora. Twitter has had bots for years, like this bot that tweets about earthquakes as soon as they’re registered or a Domino’s bot that allows you to order a pizza by tweeting a pizza emoji.
A virtual assistant is an app that comprehends natural, ordinary language voice commands and carries out tasks for the users. Well-known virtual assistants include Amazon Alexa, Apple’s Siri, Google Now and Microsoft’s Cortana. Also, virtual assistants are generally cloud-based programs so they need internet-connected devices and/or applications in order to work. Virtual assistants can perform tasks like adding calendar appointments, controlling and checking the status of a smart home, sending text messages, and getting directions.
Shane Mac, CEO of San Francisco-based Assist,warned from challenges businesses face when trying to implement chatbots into their support teams: “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.
Malicious chatbots are frequently used to fill chat rooms with spam and advertisements, by mimicking human behaviour and conversations or to entice people into revealing personal information, such as bank account numbers. They are commonly found on Yahoo! Messenger, Windows Live Messenger, AOL Instant Messenger and other instant messaging protocols. There has also been a published report of a chatbot used in a fake personal ad on a dating service's 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,…
Three main reasons are often cited for this reluctance: the first is the human side—they think users will be reluctant to engage with a bot. The other two have more to do with bots’ expected performance: there is skepticism that bots will be able to appropriately incorporate history and context to create personalized experiences and believe they won’t be able to adequately understand human input.
Like most of the Applications, the Chatbot is also connected to the Database. The knowledge base or the database of information is used to feed the chatbot with the information needed to give a suitable response to the user. Data of user’s activities and whether or not your chatbot was able to match their questions, is captured in the data store. NLP translates human language into information with a combination of patterns and text that can be mapped in the real time to find applicable responses.
Being an early adopter of a new channel can provide enormous benefits, but that comes with equally high risks. This is amplified within marketplaces like Amazon. Early adopters within Amazon's marketplace were able to focus on building a solid base of reviews for their products - a primary ranking signal - which meant that they'd create huge barriers to entry for competitors (namely because they were always showing up in the search results before them).
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".