  The burgeoning of AI has prompted recommendations that AI techniques should
be "human-centered". However, there is no clear definition of what is meant by
Human Centered Artificial Intelligence, or for short, HCAI. This paper aims to
improve this situation by addressing some foundational aspects of HCAI. To do
so, we introduce the term HCAI agent to refer to any physical or software
computational agent equipped with AI components and that interacts and/or
collaborates with humans. This article identifies five main conceptual
components that participate in an HCAI agent: Observations, Requirements,
Actions, Explanations and Models. We see the notion of HCAI agent, together
with its components and functions, as a way to bridge the technical and
non-technical discussions on human-centered AI. In this paper, we focus our
analysis on scenarios consisting of a single agent operating in dynamic
environments in presence of humans.
