revised 9/26/98, 7/27/99, 01/17/00, 04/23/00, 02/11/04, 01/10/06, 07/20/08, 05/26/14, 01/19/15
In all but the smallest programs, an executing program is constantly working with values. These values are kept in little sections of main memory called variables.
Do you imagine that a variable can change its value?