*2.3. Intelligent Virtual Agents*

Intelligent virtual agents (IVAs) powered by artificial intelligence (AI) are prevalent in our daily lives. Amazon's Alexa, Apple's Siri, and Microsoft's Cortana are all IVAs that search information in real-time and verbally communicate the results to human beings [22]. Intelligent Virtual Agents are programs that can be assigned to perform user-specified jobs in a way that is comparable to human beings, featuring reactivity, positivity [23], autonomy [24], social ability and veracity [25], etc. which is different from traditional software. It is personalized, autonomous, proactive, adaptive and continuously running.
