Mean, median, and mode are the three measures of central tendency — each describes a 'center' of a dataset differently.
**Mean (average):** Sum all values and divide by the count. Affected by outliers — one very high value pulls the mean up significantly.
**Median:** Sort all values and pick the middle one (or average of two middle values for even-count datasets). Resistant to outliers — extremely useful for income, house prices, and healthcare data where a few very large values skew the mean.
**Mode:** The value that appears most often. A dataset can have no mode (all values unique), one mode (unimodal), or multiple modes (bimodal/multimodal). Used for categorical data (most popular color, most common age in a survey) and for detecting the 'typical' repeating value.
**Example** with [10, 10, 15, 20, 100]:
• Mean: (10+10+15+20+100) ÷ 5 = 31
• Median: 15 (middle value after sorting)
• Mode: 10 (appears twice)
The mean (31) is distorted by the outlier 100. The median (15) better represents a 'typical' value in this skewed dataset.