Simple chatbots work based on pre-written keywords that they understand. Each of these commands must be written by the developer separately using regular expressions or other forms of string analysis. If the user has asked a question without using a single keyword, the robot can not understand it and, as a rule, responds with messages like “sorry, I did not understand”.
A chatbot (also known as a talkbots, chatterbot, Bot, IM bot, interactive agent, or Artificial Conversational 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 chatterbots use sophisticated natural language processing systems, but many simpler systems scan for keywords within the input, then pull a reply with the most matching keywords, or the most similar wording pattern, from a database.
Founded by Pavel Durov, creator of Russia’s equivalent to Facebook, Telegram launched in 2013 as a lightweight messaging app to combine the speed of WhatsApp with the ephemerality of Snapchat along with claimed enhanced privacy and security through its use of the MTProto protocol (Telegram has offered a $200k prize to any developer who can crack MTProto’s security). Telegram has 100M MAUs, putting it in the second tier of messaging apps in terms of popularity.
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:
Beyond users, bots must also please the messaging apps themselves. Take Facebook Messenger. Executives have confirmed that advertisements within Discover — their hub for finding new bots to engage with — will be the main way Messenger monetizes its 1.3 billion monthly active users. If standing out among the 100,000 other bots on the platform wasn't difficult enough, we can assume Messenger will only feature bots that don't detract people from the platform.
User message. Once authenticated, the user sends a message to the bot. The bot reads the message and routes it to a natural language understanding service such as LUIS. This step gets the intents (what the user wants to do) and entities (what things the user is interested in). The bot then builds a query that it passes to a service that serves information, such as Azure Search for document retrieval, QnA Maker for FAQs, or a custom knowledge base. The bot uses these results to construct a response. To give the best result for a given query, the bot might make several back-and-forth calls to these remote services.
Online chatbots save time and efforts by automating customer support. Gartner forecasts that by 2020, over 85% of customer interactions will be handled without a human. However, the opportunites provided by chatbot systems go far beyond giving responses to customers’ inquiries. They are also used for other business tasks, like collecting information about users, helping to organize meetings and reducing overhead costs. There is no wonder that size of the chatbot market is growing exponentially.
In other words, bots solve the thing we loathed about apps in the first place. You don't have to download something you'll never use again. It's been said most people stick to five apps. Those holy grail spots? They're increasingly being claimed by messaging apps. Today, messaging apps have over 5 billion monthly active users, and for the first time, people are using them more than social networks.
It’s best to have very specific intents, so that you’re clear what your user wants to do, but to have broad entities – so that the intent can apply in many places. For example, changing a password is a common activity (a narrow intent), where you change your password might be many different places (broad entities). The context then personalises the conversation based on what it knows about the user, what they’re trying to achieve, and where they’re trying to do that.
ELIZA's key method of operation (copied by chatbot designers ever since) involves the recognition of clue words or phrases in the input, and the output of corresponding pre-prepared or pre-programmed responses that can move the conversation forward in an apparently meaningful way (e.g. by responding to any input that contains the word 'MOTHER' with 'TELL ME MORE ABOUT YOUR FAMILY').[9] Thus an illusion of understanding is generated, even though the processing involved has been merely superficial. ELIZA showed that such an illusion is surprisingly easy to generate, because human judges are so ready to give the benefit of the doubt when conversational responses are capable of being interpreted as "intelligent".