Standard deviation is a statistical measure that indicates how much individual data points in a set differ from the mean (average) of that set. A low standard deviation means that the data points are close to the mean, while a high standard deviation indicates that they are spread out over a wider range of values. This concept is commonly used in various fields, including finance, science, and education, to assess variability and consistency. Understanding standard deviation helps in making informed decisions based on data analysis, as it provides insight into the reliability and predictability of the data set.