Median
The median is the middle of a distribution; half the scores are above the median and half are below. The median is less sensitive to extreme scores than the mean, which makes it a better measure for highly skewed distributions. For example, median income, where half the population is above and half below the median, is usually a more informative measure than mean income. Mean or average income would be calculated by adding the incomes of the number of people in a population and then dividing by the number of people. If a small number of people were very rich or very poor, the mean would be skewed.
See also: Mode, Standard Deviation