What does the standard deviation of a data set measure?

1. Measures of dispersion describe how widely the data are scattered. 2. The standard deviation is one of those measures. 3. It reports the average distance between the data values and the mean. 4. A small standard deviation means the data cluster tightly around the mean. 5. Where the centre lies is described by the mean or the median instead. _Source: Siyavula Mathematics Grade 12 (Everything Maths, CC BY 4.0), Chapter 9: Statistics_