Entanglement sudden death (ESD) is a phenomenon where quantum entanglement between two qubits can be completely lost in a finite time due to environmental noise, unlike the gradual decay predicted by the half-life rule. This effect, first observed in studies of dissipation, has been labeled ESD and is a new form of decay specific to quantum entanglement. ESD has been confirmed experimentally and is relevant to various quantum systems, including atomic, photonic, and spin qubits. The degradation of entanglement is a result of both classical and quantum noises, and it has been shown that the combined effect of multiple noises can lead to ESD more rapidly than individual noises. The paper reviews recent progress in understanding ESD, including its experimental verification and theoretical models. It discusses how ESD can be avoided or delayed through various methods such as quantum error correction, symmetry-based isolation, and dynamic manipulation. However, no universally effective method has been found yet. The paper also explores the possibility of "anti-ESD" or rebirth of entanglement, which can occur in certain conditions, such as in periodic systems with undamped cavities. ESD has implications for quantum information processing and storage, as it affects the preservation of quantum states. The paper also addresses the broader question of entanglement in multi-qubit systems and non-qubit systems, highlighting the challenges in understanding and controlling entanglement in complex systems. Additionally, it discusses non-Markovian noise effects and the potential for future research in entanglement dynamics, including the development of new techniques for tracking and controlling entanglement in many-qubit systems. The study emphasizes the importance of understanding ESD for the advancement of quantum technologies.Entanglement sudden death (ESD) is a phenomenon where quantum entanglement between two qubits can be completely lost in a finite time due to environmental noise, unlike the gradual decay predicted by the half-life rule. This effect, first observed in studies of dissipation, has been labeled ESD and is a new form of decay specific to quantum entanglement. ESD has been confirmed experimentally and is relevant to various quantum systems, including atomic, photonic, and spin qubits. The degradation of entanglement is a result of both classical and quantum noises, and it has been shown that the combined effect of multiple noises can lead to ESD more rapidly than individual noises. The paper reviews recent progress in understanding ESD, including its experimental verification and theoretical models. It discusses how ESD can be avoided or delayed through various methods such as quantum error correction, symmetry-based isolation, and dynamic manipulation. However, no universally effective method has been found yet. The paper also explores the possibility of "anti-ESD" or rebirth of entanglement, which can occur in certain conditions, such as in periodic systems with undamped cavities. ESD has implications for quantum information processing and storage, as it affects the preservation of quantum states. The paper also addresses the broader question of entanglement in multi-qubit systems and non-qubit systems, highlighting the challenges in understanding and controlling entanglement in complex systems. Additionally, it discusses non-Markovian noise effects and the potential for future research in entanglement dynamics, including the development of new techniques for tracking and controlling entanglement in many-qubit systems. The study emphasizes the importance of understanding ESD for the advancement of quantum technologies.