The article "Gait Variability: Methods, Modeling and Meaning" by Jeffrey M. Hausdorff provides an overview of the study of gait variability, which is the stride-to-stride fluctuations in walking. This variability is a complementary way to quantify locomotion and its changes with aging, disease, and therapeutic interventions. The article highlights that measures of gait variability may be more closely related to falls than other walking parameters. It reviews novel methods for collecting unconstrained, ambulatory data and presents analysis methods, including a heuristic approach to summarizing variability measures. The article also discusses studies on gait variability in animal models of neurodegenerative diseases and a mathematical model of human walking that characterizes multifractal features of motor control. Additionally, it explores the relationship between gait variability and fall risk, cognitive function, and dual-tasking. The article emphasizes the importance of understanding the dynamics of gait variability and its clinical utility, suggesting that it can serve as a sensitive marker for fall risk and gait instability. Finally, it addresses outstanding issues and future research directions, such as the need for standards and reference values in gait variability studies.The article "Gait Variability: Methods, Modeling and Meaning" by Jeffrey M. Hausdorff provides an overview of the study of gait variability, which is the stride-to-stride fluctuations in walking. This variability is a complementary way to quantify locomotion and its changes with aging, disease, and therapeutic interventions. The article highlights that measures of gait variability may be more closely related to falls than other walking parameters. It reviews novel methods for collecting unconstrained, ambulatory data and presents analysis methods, including a heuristic approach to summarizing variability measures. The article also discusses studies on gait variability in animal models of neurodegenerative diseases and a mathematical model of human walking that characterizes multifractal features of motor control. Additionally, it explores the relationship between gait variability and fall risk, cognitive function, and dual-tasking. The article emphasizes the importance of understanding the dynamics of gait variability and its clinical utility, suggesting that it can serve as a sensitive marker for fall risk and gait instability. Finally, it addresses outstanding issues and future research directions, such as the need for standards and reference values in gait variability studies.