This paper provides a comprehensive survey of LLM-based AI chatbots, covering their evolution, deployment, and applications across various sectors. It begins by summarizing the development of foundational chatbots and the evolution of LLMs, followed by an overview of current and developing LLM-based chatbots. The paper explores the diverse applications of these chatbots in education, research, healthcare, software engineering, and finance, highlighting their impact on operational dynamics and user interactions. It discusses the challenges and ethical considerations associated with the widespread use of LLM-based chatbots, including data transparency, bias, privacy risks, and misuse. The paper also outlines future prospects for improving the efficiency and reliability of LLM-based chatbots, emphasizing the importance of technical advancements and ethical guidelines. By addressing key milestones and the present-day context, the survey aims to provide readers with a deeper understanding of LLM-based chatbots and their potential to reshape conversational AI.This paper provides a comprehensive survey of LLM-based AI chatbots, covering their evolution, deployment, and applications across various sectors. It begins by summarizing the development of foundational chatbots and the evolution of LLMs, followed by an overview of current and developing LLM-based chatbots. The paper explores the diverse applications of these chatbots in education, research, healthcare, software engineering, and finance, highlighting their impact on operational dynamics and user interactions. It discusses the challenges and ethical considerations associated with the widespread use of LLM-based chatbots, including data transparency, bias, privacy risks, and misuse. The paper also outlines future prospects for improving the efficiency and reliability of LLM-based chatbots, emphasizing the importance of technical advancements and ethical guidelines. By addressing key milestones and the present-day context, the survey aims to provide readers with a deeper understanding of LLM-based chatbots and their potential to reshape conversational AI.