A variable is a name given to a memory location where the data can be stored. Using the variable name, the data can be stored in memory location and can be accessed or manipulated very easily.
Every variable should be associated with type,size, and value.whenever a new value should be placed into a variable,then it replace a previous Value. When variable was reading from the memory it dose not change them.the value was store in the variable may be change during execution of the program.
Rules for defining a variable:-
The first character in the variable should be a letter (from a to z or A to Z) or an underscore.
The first character can be followed by any number of letters or digits( 0 to 9) or underscores.
No extra symbols are allowed other than letters, digits, and underscore.