The concept of variables:
It occupies a certain storage area in the memory;
The region has its own name (variable name) and type (data type);
The data area may vary continuously within a range of the same type;
Why do you want to define variables:
To continue the same type of stored constants, and can be reused;
Note the use of variables:
Scope of variables, initialization values
Define the variable format:
Data type variable name = initial value;
Note: The format is fixed, remember format, maintaining the status quo.
Range: defining the start to the end of its defined code blocks;
In the same range, it does not allow multiple local variable naming conflicts