typedef statement 

It is used to redefine the name of an existing variable type.

typedef long int NUMBER

now we can declare variables of the type long int by writing-

NUMBER num1,num2;

typedef provide a short and meaningful way to call a data type. Usually, uppercase letters are used to make it clear that we are dealing with a renamed data type.

struct employee

{

                char name[20];

                int age;

};

typedef struct employee EMP;

EMP e1,e2;

typedef statement provides a short and meaningful way to call a data type. Its purpose is to redefine the name of an existing variable type. Typedef may be used with any data type. Its general format is as follows :

Syntax :

typedef  <existing datatype>  <new datatype>;

Example :

typedef  int  itech;

itech a,b,c;   /* declare a, b,c  as int variable */