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”.
Yes. Messenger bots are approved by Facebook before being made available inside the Messenger app so you can rest assured that they aren’t trying to steal your identity (or anything else). What’s more is a bot is tied to a Facebook page and a Facebook app making it all the more inconvenient to use for fraudulent activity. That said, don’t exchange private and/or personal information with a bot. Finally, because Messenger doesn’t support credit cards and purchasing just yet, anything you buy will likely be done via a browser with a bot aiding you so far as to place an order. If you want, you can always block a bot.