The range is an important statistical concept.  Thus, it is
important to define range.  What is the range? Below is a
range definition with respect to statistics.

Range Definition:

The range is the difference between the highest number
and lowest number in a set of numbers.

Range Example:

Imagine that you conducted a scientific study in which
participants completed a personality measure.   There were
20 participants in the study.   Below are the scores for the
20 participants with respect to the personality measure:

19, 22, 28, 22, 17, 13, 11, 29, 21, 20, 18, 29, 30, 23, 22,
21, 24, 23, 20, 19.

The lowest number among the above 20 numbers is 11, and
the highest number of among the above numbers is 30.  
Thus, the range in this example is 19.  This is the difference
between the highest and lower numbers.