The standard deviation is a statistical measure that quantifies the amount of variation or dispersion in a set of values. A low standard deviation indicates that the values tend to be close to the mean (average), while a high standard deviation suggests that the values are spread out over a wider range. In practical terms, standard deviation helps to understand how much individual data points differ from the average. It is commonly used in various fields, including finance, science, and social sciences, to assess risk, variability, and consistency in data sets.