This review article, titled "Zonal Flows in Plasma—a Review," published in Plasma Physics and Controlled Fusion, provides a comprehensive overview of zonal flow phenomena in both laboratory and planetary plasmas. The authors, P. H. Diamond, S.-I. Itoh, K. Itoh, and T. S. Hahm, discuss the dynamics of zonal flows, their role in plasma confinement, and their implications for fusion devices. The review emphasizes the integration of theory, numerical simulations, and experimental results to understand the complex interactions between drift waves and zonal flows. It highlights the importance of zonal flows in regulating turbulence and transport in plasmas, particularly in low collisionality regimes. The article also explores the connection between zonal flows and self-organization processes in nature, drawing parallels with phenomena such as planetary atmospheric dynamics and magnetic dynamos. The review discusses various theoretical models, including wave kinetic theory, parametric theory, and envelope formalism, and presents a detailed analysis of zonal flow generation, shearing, and feedback mechanisms. It also addresses the impact of zonal flows on turbulent transport and their role in the formation of transport barriers. The study concludes with a discussion of the broader implications of zonal flow dynamics for plasma physics and fusion research, emphasizing the need for further investigation into the nonlinear interactions and self-regulation mechanisms of zonal flows. The review is dedicated to the memory of Professor Marshall N. Rosenbluth and includes appendices that provide additional insights into the theoretical foundations of zonal flow dynamics.This review article, titled "Zonal Flows in Plasma—a Review," published in Plasma Physics and Controlled Fusion, provides a comprehensive overview of zonal flow phenomena in both laboratory and planetary plasmas. The authors, P. H. Diamond, S.-I. Itoh, K. Itoh, and T. S. Hahm, discuss the dynamics of zonal flows, their role in plasma confinement, and their implications for fusion devices. The review emphasizes the integration of theory, numerical simulations, and experimental results to understand the complex interactions between drift waves and zonal flows. It highlights the importance of zonal flows in regulating turbulence and transport in plasmas, particularly in low collisionality regimes. The article also explores the connection between zonal flows and self-organization processes in nature, drawing parallels with phenomena such as planetary atmospheric dynamics and magnetic dynamos. The review discusses various theoretical models, including wave kinetic theory, parametric theory, and envelope formalism, and presents a detailed analysis of zonal flow generation, shearing, and feedback mechanisms. It also addresses the impact of zonal flows on turbulent transport and their role in the formation of transport barriers. The study concludes with a discussion of the broader implications of zonal flow dynamics for plasma physics and fusion research, emphasizing the need for further investigation into the nonlinear interactions and self-regulation mechanisms of zonal flows. The review is dedicated to the memory of Professor Marshall N. Rosenbluth and includes appendices that provide additional insights into the theoretical foundations of zonal flow dynamics.