typedef declaration helps to make source code of a C program more readable. Its purpose is to redefine the name of an existing variable type. It provides a short and meaningful way to call a data type. typedef is useful when the name of the data type is long. Use of typedef can reduce length and complexity of data types.

Note: Usually uppercase letters are used to make it clear that we are dealing with our own data type.

Example:

struct employee {

char name[20];

int age;

};