1. The **measures of central tendency** (mean, median, mode) help us find a single value that represents the center or typical value of a data set. 2. These measures summarize the data with one number, making it easier to understand and compare different data sets. 3. The **mean** is the average, calculated by adding all values and dividing by the number of values, showing the overall level. 4. The **median** is the middle value when data is ordered, useful when data has outliers or is skewed. 5. The **mode** is the most frequent value, helpful for categorical data or identifying common values. 6. The **measures of variability** (range, variance, standard deviation) describe how spread out or dispersed the data values are. 7. Variability tells us if data points are close to the center or widely spread, which affects reliability and interpretation. 8. The **range** is the difference between the maximum and minimum values, showing the total spread. 9. The **variance** measures the average squared deviation from the mean, quantifying overall spread. 10. The **standard deviation** is the square root of variance, giving spread in the same units as the data. 11. Together, central tendency and variability provide a complete summary: where data centers and how much it varies. This helps in making informed decisions, comparing groups, and understanding data patterns.