It is one method to calculate an "average" number. Median is the middle value of the given numbers or distribution in their ascending order. So if you have an odd series of numbers, it is the middle number. If you have an even series of numbers, it is the average of the two middle elements. See a site called easy calculation to see the method used to calculate a median number.
Median goes together with mean and mode gives us three ways to calculate averages. The mean of a series of numbers is your usual average. That is you add up all the numbers and then divide that number by the number of numbers in the series. The mode of a series of numbers is the one number most frequently repeated.
Most of the calculations I use in my spreadsheets are median calculations. This is a current preferred way of many analysts to compare current ratios to historical ratios.
This blog is meant for educational purposes only, and is not to provide investment advice. Before making any investment decision, you should always do your own research or consult an investment professional. See my site for an index to these blog entries and for stocks followed. Follow me on Twitter.