Characteristics of variables:

Variables are characterized by:

- Name (identifier) ,for example age;

- Type (of information preserved in them), for example int;
- Value (stored information) for example 25.

A variable is a named area of memory ,which stores a value from a particular data type , and that area of memory is accessible in the program by its name , variables can be stored directly in the operationa memory of the program  (in the stack ) or in the dynamic memory in which larger objects are stored (such as character strings and arrays).
Primitive data types ( numbers ,char, bool ) are called value type because they stored their value directly in the program stack.
Reference data types (such as strings , objects  and arrays ) are an address pointing to the dynamic memory where their value is stored .They can be dynamically allocated and released i.e. their size is not fixed in advance contrary to the case of value types.