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”.
24/7 digital support. An instant and always accessible assistant is assumed by the more and more digital consumer of the new era.[34] Unlike humans, chatbots once developed and installed don't have a limited workdays, holidays or weekends and are ready to attend queries at any hour of the day. It helps to the customer to avoid waiting of a company's agent to be available. Thus, the customer doesn't have to wait for the company executive to help them. This also lets companies keep an eye on the traffic during the non-working hours and reach out to them later.[41]
A.L.I.C.E. was written within the frame of Artificial Intelligence Markup Language (AIML), an open standard for creating any kind of chatbot, also developed by Wallace. Most AIML interpreters are offered under a free or open source license. Therefore, many “Alicebot clones” populate the internet, having been created based upon the original implementation of A.L.I.C.E. and its AIML knowledge base. This video shows a speech as given by dr. Wallace about A.L.I.C.E., AIML and the chatbot history in general.
1. Define the goals. What should your chatbot do? Clearly indicate the list of functions your chatbot needs to perform. 2. Choose a channel to interact with your customers. Be where your clients prefer to communicate — your website, mobile app, Facebook Messenger, WhatsApp or other messaging platform. 3. Choose the way of creation. There are two of them: using readymade chat bot software or building a custom bot from scratch. 4. Create, customize and launch. Describe the algorithm of its actions, develop a database of answers and test the work of the chatbot. Double check everything before showing your creation to potential customers.

According to the Journal of Medical Internet Research, "Chatbots are [...] increasingly used in particular for mental health applications, prevention and behavior change applications (such as smoking cessation or physical activity interventions).".[48] They have been shown to serve as a cost-effective and accessible therapeutic agents for indications such as depression and anxiety.[49] A conversational agent called Woebot has been shown to significantly reduce depression in young adults.[50]

This chatbot aims to make medical diagnoses faster, easier, and more transparent for both patients and physicians – think of it like an intelligent version of WebMD that you can talk to. MedWhat is powered by a sophisticated machine learning system that offers increasingly accurate responses to user questions based on behaviors that it “learns” by interacting with human beings.

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]
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.) 
Several studies accomplished by analytics agencies such as Juniper or Gartner [34] report significant reduction of cost of customer services, leading to billions of dollars of economy in the next 10 years. Gartner predicts an integration by 2020 of chatbots in at least 85% of all client's applications to customer service. Juniper's study announces an impressive amount of $8 billion retained annually by 2022 due to the use of chatbots.
The word bot, in Internet sense, is a short form of robot and originates from XX century. The modern use of the word bot has curious affinities with earlier uses, e.g. “parasitical worm or maggot” (1520s), of unknown origin; and Australian-New Zealand slang “worthless, troublesome person” (World War I -era). The method of minting new slang by clipping the heads off respectable words does not seem to be old or widespread in English. Examples: za from pizza, zels from pretzels, rents from parents, are American English student or teen slang and seem to date back no further than late 1960s.[3]
In the early 90’s, the Turing test, which allows determining the possibility of thinking by computers, was developed. It consists in the following. A person talks to both the person and the computer. The goal is to find out who his interlocutor is — a person or a machine. This test is carried out in our days and many conversational programs have coped with it successfully.
Unfortunately, my mom can’t really engage in meaningful conversations anymore, but many people suffering with dementia retain much of their conversational abilities as their illness progresses. However, the shame and frustration that many dementia sufferers experience often make routine, everyday talks with even close family members challenging. That’s why Russian technology company Endurance developed its companion chatbot.
Despite the fact that ALICE relies on such an old codebase, the bot offers users a remarkably accurate conversational experience. Of course, no bot is perfect, especially one that’s old enough to legally drink in the U.S. if only it had a physical form. ALICE, like many contemporary bots, struggles with the nuances of some questions and returns a mixture of inadvertently postmodern answers and statements that suggest ALICE has greater self-awareness for which we might give the agent credit.
Derived from “chat robot”, "chatbots" allow for highly engaging, conversational experiences, through voice and text, that can be customized and used on mobile devices, web browsers, and on popular chat platforms such as Facebook Messenger, or Slack. With the advent of deep learning technologies such as text-to-speech, automatic speech recognition, and natural language processing, chatbots that simulate human conversation and dialogue can now be found in call center and customer service workflows, DevOps management, and as personal assistants.

Have you ever dreamed about creating your own chat bot that asks users a few simple questions and, based on human replies, creates new questions to continue the conversation, possibly an endless conversation? Have you thought about putting this chat bot on your Facebook page? Nothing simpler than creating a chat bot by reading and following this step-by-step guide Writing your first Facebook chat bot in PHP using Jaxl library written by a PHP developer Abhinav Singh.
Jabberwacky learns new responses and context based on real-time user interactions, rather than being driven from a static database. Some more recent chatbots also combine real-time learning with evolutionary algorithms that optimise their ability to communicate based on each conversation held. Still, there is currently no general purpose conversational artificial intelligence, and some software developers focus on the practical aspect, information retrieval.