This review discusses quantum information with continuous variables, focusing on quantum optical implementations using the quadrature amplitudes of the electromagnetic field. It covers the theoretical foundations, experimental implementations, and applications in quantum communication and computation. The article begins with an introduction to the field, emphasizing the importance of continuous variables in quantum information theory. It then explores the properties of continuous variables in quantum optics, including quadratures, phase-space representations, Gaussian states, and linear and nonlinear optics. The review discusses continuous-variable entanglement, including bipartite and multipartite entanglement, bound entanglement, and nonlocality. It also covers quantum communication protocols such as quantum teleportation, dense coding, and quantum cryptography, as well as quantum cloning and computation with continuous variables. The article highlights the advantages of continuous-variable approaches, such as their high efficiency and unconditionalness, and discusses the challenges and trade-offs involved in their implementation. It also reviews experimental demonstrations of continuous-variable quantum information processing, including the generation of squeezed-state entanglement, long-lived atomic entanglement, and quantum teleportation. The review concludes with a discussion of the future prospects and challenges in the field of continuous-variable quantum information.This review discusses quantum information with continuous variables, focusing on quantum optical implementations using the quadrature amplitudes of the electromagnetic field. It covers the theoretical foundations, experimental implementations, and applications in quantum communication and computation. The article begins with an introduction to the field, emphasizing the importance of continuous variables in quantum information theory. It then explores the properties of continuous variables in quantum optics, including quadratures, phase-space representations, Gaussian states, and linear and nonlinear optics. The review discusses continuous-variable entanglement, including bipartite and multipartite entanglement, bound entanglement, and nonlocality. It also covers quantum communication protocols such as quantum teleportation, dense coding, and quantum cryptography, as well as quantum cloning and computation with continuous variables. The article highlights the advantages of continuous-variable approaches, such as their high efficiency and unconditionalness, and discusses the challenges and trade-offs involved in their implementation. It also reviews experimental demonstrations of continuous-variable quantum information processing, including the generation of squeezed-state entanglement, long-lived atomic entanglement, and quantum teleportation. The review concludes with a discussion of the future prospects and challenges in the field of continuous-variable quantum information.