Gaussian states are a class of quantum states that are fully characterized by their first and second moments, making them particularly easy to manipulate and analyze. They are characterized by a Gaussian probability distribution in phase space and can be thought of as the quantum analog of classical Gaussian distributions. Gaussian states are commonly used in quantum optics, quantum information theory, and quantum computing due to their simplicity and tractability. They are often used as a starting point for more complex quantum systems and are useful for studying issues such as quantum entanglement, teleportation, and quantum key distribution. Overall, Gaussian states play a crucial role in quantum information processing and offer a valuable framework for studying quantum systems and their properties.