When testing a program it is important to use a range of data to ensure the program works as expected.
For the examples below we will assume that the user has been asked to enter their age in years.
This should be typical data that you would expect a user to enter. (e.g. 7, 11,43,65)
Boundary /Extreme Data
This should be data at the limits of what you would expect a user to enter (e.g. 0, 1, 115, 120)
This is data that should not be entered and should be rejected by the program (e.g. -7, 87858.35, Z, True, Brian)