Conversational Artificial Intelligence (CAI) is the backbone of digital systems that can engage in human-like dialogue, understand context, decipher intent, and respond in a manner that mimics human conversation. Bridging the communication gap between humans and machines, CAI has revolutionized how we interact with technology. In this chapter, we introduce the overview of the field of Conversational AI, the types of conversational agents, and the history of technological developments in the field. The journey begins with the rudimentary text-based chatbots of the mid-20th century and ends with the modern, sophisticated versions that utilize machine learning. We discuss the evolution of voicebots, from simple voice response systems to the current virtual assistants that comprehend and respond to complex voice commands. The chapter concludes with an in-depth exploration of the emergence of conversational large language models fine-tuned with reinforcement learning and human feedback (RLHF).