What is the difference between mean, mode, and median?

Mean, mode, and median are different types of averages. The mode is the most commonly occuring element in a sample. The median is the element occuring at the 50th percentile, or halfway through an ordered sample, and is therefore resistant to outliers. Mean is found by summing all of the values in a sample and dividing that total by the count of the items in the sample. Mean is perhaps the most common colloquial meaning of the word "average", but is less resistant to outliers than both mode and median.