Some brands already seem to be getting the balance right. A bot needs to capture a user's attention quickly and display a healthy curiosity about their new acquaintance, but too much curiosity can easily push them into creepy territory and turn people off. They have to display more than a basic knowledge of human conversational patterns, but they can't claim to be an actual human -- again, let's keep things from getting too creepy here.
For designing a chatbot conversation, you can refer this blog — “How to design a conversation for chatbots.” Chatbot interactions are segmented into structured and unstructured interactions. As the name suggests, the structured type is more about the logical flow of information, including menus, choices, and forms into account. The unstructured conversation flow includes freestyle plain text. Conversations with family, colleagues, friends and other acquaintances fall into this segment. Developing scripts for these messages will follow suit. While developing the script for messages, it is important to keep the conversation topics close to the purpose served by the chatbot. For the designer, interpreting user answers is important to develop scripts for a conversational user interface. The designer also turns their attention to close-ended conversations that are easy to handle and open-ended conversations that allow customers to communicate naturally.
Context: When a NLU algorithm analyzes a sentence, it does not have the history of the user conversation. It means that if it receives the answer to a question it has just asked, it will not remember the question. For differentiating the phases during the chat conversation, it’s state should be stored. It can either be flags like “Ordering Pizza” or parameters like “Restaurant: ‘Dominos’”. With context, you can easily relate intents with no need to know what was the previous question.

Multinational Naive Bayes is the classic algorithm for text classification and NLP. For an instance, let’s assume a set of sentences are given which are belonging to a particular class. With new input sentence, each word is counted for its occurrence and is accounted for its commonality and each class is assigned a score. The highest scored class is the most likely to be associated with the input sentence.
The classic historic early chatbots are ELIZA (1966) and PARRY (1972).[5] 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).[6]

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
One pertinent field of AI research is natural language processing. Usually, weak AI fields employ specialized software or programming languages created specifically for the narrow function required. For example, A.L.I.C.E. uses a markup language called AIML, which is specific to its function as a conversational agent, and has since been adopted by various other developers of, so called, Alicebots. Nevertheless, A.L.I.C.E. is still purely based on pattern matching techniques without any reasoning capabilities, the same technique ELIZA was using back in 1966. This is not strong AI, which would require sapience and logical reasoning abilities.