**Standard Deviation** is the statistical concept used to quantify the dispersion or spread of data in a normal distribution. It measures how much individual data points deviate from the mean (average) of the dataset. A higher standard deviation indicates greater variability or spread in the data, while a lower standard deviation suggests data points are clustered closer to the mean. **Normal Distribution**, also known as the bell curve, is a probability distribution where the majority of the data points cluster around the mean, with fewer data points further away from the mean. **SEO Keywords:** Standard Deviation, Normal Distribution, Dispersion, Spread, Data Analysis, Statistics