A variable refers to a quantity whose name is an identifier and whose value can be changed. A variable represents a certain storage unit in the computer's memory, and the data stored in the storage unit is the value of the variable. If there is a variable a in the program, then a is the name of a certain storage unit. The user's operation on variable a is the operation on the storage unit; assigning a value to variable a means storing the data in the storage unit represented by variable a. middle.