Virtual Personal Assistants (VPA) are software program meant to interact with an end user in a natural way, to answer questions, follow a conversation and accomplish different tasks.
Two kinds of inputs are usually possible for a VPA: a voice interface (such as Apple Siri) or a text interface (Google Assistant). The key point is that the end user is supposed to be able to talk to the VPA using his natural language, that is, as he would do to another human being rather than having to use specific sets of commands or a computer language.
Since the launch of Siri by Apple in2011, the offers of virtual personal assistants have developed rapidly to provide a more generic user interface. This user interface can be accessed from the user device (smartphone or specific device) to perform actions, control objects, answer question and even make recommendations on its own.