What Is Mean, Median, and Mode?
Mean is the arithmetic average — add up all the values and divide by how many there are. Median is the middle value when the data is sorted (or the average of the two middle values if there's an even count). Mode is the value that appears most often. Each measures "center" differently, and they can give very different answers on skewed data.
Example
For the data set 2, 3, 3, 5, 20: the mean is 6.6 (33 ÷ 5), the median is 3 (the middle value when sorted), and the mode is 3 (it appears twice). The single high value of 20 pulls the mean up but doesn't affect the median or mode.