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.…
When one dialog invokes another, the Bot Builder adds the new dialog to the top of the dialog stack. The dialog that is on top of the stack is in control of the conversation. Every new message sent by the user will be subject to processing by that dialog until it either closes or redirects to another dialog. When a dialog closes, it's removed from the stack, and the previous dialog in the stack assumes control of the conversation.

Ultimately, only time will tell how effective the likes of Facebook Messenger will become in the long term. As more and more companies look to use chatbots within the platform, the greater the frequency of messages that individual users will receive. This could result in Facebook (and other messaging platforms) placing stricter restrictions on usage, but until then I'd recommend testing as much as possible.

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.
As AOL's David Shingy writes in Adweek, "The challenge [with chatbots] will be thinking about creative from a whole different view: Can we have creative that scales? That customizes itself? We find ourselves hurtling toward another handoff from man to machine -- what larger system of creative or complex storytelling structure can I design such that a machine can use it appropriately and effectively?"
A chatbot (also known as a spy, conversational bot, chatterbot, interactive agent, conversational interface, Conversational AI, talkbot or artificial spy 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 chatbots use sophisticated natural language processing systems, but many simpler ones scan for keywords within the input, then pull a reply with the most matching keywords, or the most similar wording pattern, from a database.