  In this chapter, we provide a review of conversational agents (CAs),
discussing chatbots, intended for casual conversation with a user, as well as
task-oriented agents that generally engage in discussions intended to reach one
or several specific goals, often (but not always) within a specific domain. We
also consider the concept of embodied conversational agents, briefly reviewing
aspects such as character animation and speech processing. The many different
approaches for representing dialogue in CAs are discussed in some detail, along
with methods for evaluating such agents, emphasizing the important topics of
accountability and interpretability. A brief historical overview is given,
followed by an extensive overview of various applications, especially in the
fields of health and education. We end the chapter by discussing benefits and
potential risks regarding the societal impact of current and future CA
technology.
