The median is the middle value in a set of sorted values. For example, 6 is the median of 1, 3, 6, 7, and 9 (recall that the mean is 5.2).
If an odd number of values exists, you find the median by ordering the values from smallest to largest and then selecting the middle value.
If an even number of values exists, then the median is the mean of the two middle values.