In a traditional application, the user interface (UI) consists of a series of screens, and a single app or website can use one or more screens as needed to exchange information with the user. Most applications start with a main screen where users initially land, and that screen provides navigation that leads to other screens for various functions like starting a new order, browsing products, or looking for help.

From any point in the conversation, the bot needs to know where to go next. If a user writes, “I’m looking for new pants,” the bot might ask, “For a man or woman?” The user may type, “For a woman.” Does the bot then ask about size, style, brand, or color? What if one of those modifiers was already specified in the query? The possibilities are endless, and every one of them has to be mapped with rules.

Smart chatbots rely on artificial intelligence when they communicate with users. Instead of pre-prepared answers, the robot responds with adequate suggestions on the topic. In addition, all the words said by the customers are recorded for later processing. However, the Forrester report “The State of Chatbots” points out that artificial intelligence is not a magic and is not yet ready to produce marvelous experiences for users on its own. On the contrary, it requires a huge work:
Chatfuel is one of the leading chatbot development platforms to develop chatbots for Facebook Messenger. One of the main reasons of Chatfuel’s popularity is easy to use interface. No knowledge of programming is required to create basic chatbot. People with non-technical background too can create bots using the platform and launch on their Facebook page.…
What if you’re creating a bot for a major online clothing retailer? For starters, the bot will require a greeting (“How can I help you?”) as well as a process for saying its goodbyes. In between, the bot needs to respond to inputs, which could range from shopping inquiries to questions about shipping rates or return policies, and the bot must possess a script for fielding questions it doesn’t understand.
Conversational bots work in a similar way as an employee manning a customer care desk. When a customer asks for assistance, the conversational bot is the medium responding. If a customer asks the question, “What time does your store close on Friday?” the conversational bot would respond the same as a human would, based on the information available. “Our store closes at 5pm on Friday.”
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,…
ELIZA's key method of operation (copied by chatbot designers ever since) involves the recognition of cue 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'). 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".

The classic historic early chatbots are ELIZA (1966) and PARRY (1972).[10][11][12][13] More recent notable programs include A.L.I.C.E., Jabberwacky and D.U.D.E (Agence Nationale de la Recherche and CNRS 2006). While ELIZA and PARRY were used exclusively to simulate typed conversation, many chatbots now include functional features such as games and web searching abilities. In 1984, a book called The Policeman's Beard is Half Constructed was published, allegedly written by the chatbot Racter (though the program as released would not have been capable of doing so).[14]