Eddy Covariance is a method used to measure the exchange of gases between the Earth's surface and the atmosphere. This book provides a comprehensive guide to the measurement and data analysis of eddy covariance. It is edited by Prof. Marc Aubinet, Prof. Timo Vesala, and Dr. Dario Papale. The book was developed in response to the need for standardization in eddy covariance measurements, which became evident with the development of eddy covariance networks in the mid-1990s. The book aims to provide theoretical and practical information necessary for developing eddy covariance measurements, from site installation to data treatment. The book is structured into 17 chapters, covering topics such as the theoretical basis of the eddy covariance method, technical requirements for the eddy covariance setup, data acquisition and flux calculations, corrections and data quality control, nighttime flux correction, data gap filling, uncertainty quantification, footprint analysis, partitioning of net fluxes, disjunct eddy covariance method, eddy covariance measurements over forests, crops, grasslands, wetlands, lakes, and urban areas, as well as database maintenance, data sharing policies, and collaboration. The book is a result of a two-and-a-half-year-long effort by a team of experts in the field. It is intended to help practitioners in the field of eddy covariance measurements and to contribute to the development of eddy covariance networks worldwide. The book also includes a list of references, a symbol index, and an index of abbreviations and acronyms. The editors thank the co-authors for their contributions and acknowledge the support from the IMECC EU project and the ABBA Cost Action. The book is dedicated to the field technicians and Ph.D. students who contribute to ecosystem studies through these measurements.Eddy Covariance is a method used to measure the exchange of gases between the Earth's surface and the atmosphere. This book provides a comprehensive guide to the measurement and data analysis of eddy covariance. It is edited by Prof. Marc Aubinet, Prof. Timo Vesala, and Dr. Dario Papale. The book was developed in response to the need for standardization in eddy covariance measurements, which became evident with the development of eddy covariance networks in the mid-1990s. The book aims to provide theoretical and practical information necessary for developing eddy covariance measurements, from site installation to data treatment. The book is structured into 17 chapters, covering topics such as the theoretical basis of the eddy covariance method, technical requirements for the eddy covariance setup, data acquisition and flux calculations, corrections and data quality control, nighttime flux correction, data gap filling, uncertainty quantification, footprint analysis, partitioning of net fluxes, disjunct eddy covariance method, eddy covariance measurements over forests, crops, grasslands, wetlands, lakes, and urban areas, as well as database maintenance, data sharing policies, and collaboration. The book is a result of a two-and-a-half-year-long effort by a team of experts in the field. It is intended to help practitioners in the field of eddy covariance measurements and to contribute to the development of eddy covariance networks worldwide. The book also includes a list of references, a symbol index, and an index of abbreviations and acronyms. The editors thank the co-authors for their contributions and acknowledge the support from the IMECC EU project and the ABBA Cost Action. The book is dedicated to the field technicians and Ph.D. students who contribute to ecosystem studies through these measurements.