Recent advances in large language models (LLMs) and the intensifying popularity of AI-empowered chatbot applications have blurred the boundary of high-quality text generation between humans and machines. However, in addition to the anticipated revolutionary changes to our technology and society, the difficulty of distinguishing LLM-generated texts (AI-text) from human-generated texts poses new challenges of misuse and fairness, such as deepfakes, fake content generation, plagiarism, and false accusations of innocent writers. This chapter presents a suite of AI-text detectors.