This article presents a consensus update on the phenomenology and classification of dystonia, based on input from an international panel of experts. Dystonia is defined as a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. It is classified along two axes: clinical characteristics (age at onset, body distribution, temporal pattern, and associated features) and etiology (nervous system pathology and inheritance). The clinical characteristics fall into several specific dystonia syndromes that help guide diagnosis and treatment. The article discusses the evolution of dystonia classification over time, highlighting the need for a more accurate and comprehensive classification system. It addresses the limitations of previous classifications, particularly the use of terms like "primary" and "secondary" dystonia, which can be ambiguous. The authors propose a revised classification that distinguishes clinical features from etiology, aiming to improve diagnostic and therapeutic approaches. The article also discusses the classification of inherited and acquired dystonias, including specific genetic disorders such as DYT1, DYT5, DYT6, and others. It highlights the importance of distinguishing between different types of dystonia, such as focal, segmental, and generalized forms, as well as the presence of associated features like myoclonus, parkinsonism, or other movement disorders. The authors emphasize the need for a more accurate and comprehensive classification system that reflects the current understanding of dystonia's phenomenology and etiology. They propose a new definition of dystonia that incorporates the most recent findings and aims to improve the accuracy of diagnosis and treatment. The article concludes with a call for the adoption of the new classification system in clinical practice and research.This article presents a consensus update on the phenomenology and classification of dystonia, based on input from an international panel of experts. Dystonia is defined as a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. It is classified along two axes: clinical characteristics (age at onset, body distribution, temporal pattern, and associated features) and etiology (nervous system pathology and inheritance). The clinical characteristics fall into several specific dystonia syndromes that help guide diagnosis and treatment. The article discusses the evolution of dystonia classification over time, highlighting the need for a more accurate and comprehensive classification system. It addresses the limitations of previous classifications, particularly the use of terms like "primary" and "secondary" dystonia, which can be ambiguous. The authors propose a revised classification that distinguishes clinical features from etiology, aiming to improve diagnostic and therapeutic approaches. The article also discusses the classification of inherited and acquired dystonias, including specific genetic disorders such as DYT1, DYT5, DYT6, and others. It highlights the importance of distinguishing between different types of dystonia, such as focal, segmental, and generalized forms, as well as the presence of associated features like myoclonus, parkinsonism, or other movement disorders. The authors emphasize the need for a more accurate and comprehensive classification system that reflects the current understanding of dystonia's phenomenology and etiology. They propose a new definition of dystonia that incorporates the most recent findings and aims to improve the accuracy of diagnosis and treatment. The article concludes with a call for the adoption of the new classification system in clinical practice and research.