Conversational AI has seen a growing interest among government, researchers, and industrialists. This comprehensive survey paper provides an in-depth analysis of large language models, specifically focusing on ChatGPT. This paper discusses the architecture, training process, and challenges associated with large language models, including bias, interpretability, and ethics. It explores various applications of ChatGPT and examines future research trends, such as improving model generalization, addressing data scarcity, and integrating multimodal capabilities. This survey also serves as a roadmap for researchers, practitioners, and policymakers, offering valuable insights into the current state and future potential of large language models and ChatGPT.