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. 
The NLP system has a wide and varied lexicon to better understand the complexities of natural language. Using an algorithmic process, it determines what has been asked and uses decision trees or slot-based algorithms that go through a predefined conversation path. After it understands the question, the computer then finds the best answer and provides it in the natural language of the user.
An AI-powered chatbot is a smarter version of a chatbot (a machine that has the ability to communicate with humans via text or audio). It uses natural language processing (NLP) and machine learning (ML) to get a better understanding of the intent of humans it interacts with. Also, its purpose is to provide a natural, as near human-level communication as possible.
There are obvious revenue opportunities around subscriptions, advertising and commerce. If bots are designed to save you time that you’d normally spend on mundane tasks or interactions, it’s possible they’ll seem valuable enough to justify a subscription fee. If bots start to replace some of the functions that you’d normally use a search engine like Google for, it’s easy to imagine some sort of advertising component. Or if bots help you shop, the bot-maker could arrange for a commission.
ALICE – which stands for Artificial Linguistic Internet Computer Entity, an acronym that could have been lifted straight out of an episode of The X-Files – was developed and launched by creator Dr. Richard Wallace way back in the dark days of the early Internet in 1995. (As you can see in the image above, the website’s aesthetic remains virtually unchanged since that time, a powerful reminder of how far web design has come.)
Let’s take a weather chat bot as an example to examine the capabilities of Scripted and Structured chatbots. The question “Will it rain on Sunday?” can be easily answered. However, if there is no programming for the question “Will I need an umbrella on Sunday?” then the query will not be understood by the chat bot. This is the common limitation with scripted and structured chatbots. However, in all cases, a conversational bot can only be as intelligent as the programming it has been given.
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'). 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".