This chapter explores the emergence and evolution of AI Agents, marking a significant shift in artificial intelligence. It defines AI Agents as highly autonomous, adaptive digital entities capable of complex reasoning and action in various environments. The chapter traces the historical development of AI, from early problem-solving programs to modern, sophisticated systems. It presents a taxonomy of AI Agents, including reactive, deliberative, hybrid, learning, cognitive, collaborative, competitive, and domain-specific agents. The chapter highlights recent technological advancements enabling the current AI Agent renaissance, such as increased computational power and breakthroughs in natural language processing. It also discusses cutting-edge research from OpenAI and Stanford University, showcasing projects like OpenAI’s Operator Agent and Stanford’s Self-Taught Reasoner (STaR). The chapter concludes by considering the transformative potential of AI Agents across various fields and the ethical implications of their development.