Ref Cursor is a variable of type cursor. It is a pointer to work area of the result set obtained by executing a select statement.

Steps to create and use the ref cursor.

1. Define the variable of type REF CURSOR
2. Pass that variable to a procedure or function which actually executest the sql statement for the cursor and returns the cursor variable as OUT variable.

You must pass the ref cursor variable type as IN OUT argument to the stored procedure or function.
 

Creating Package Spec
Create or replace package customer_info as
  --This is the way you define a variable of type REF CURSOR
  TYPE cust_data_cursor IS REF CURSOR;
 --Now we can send this variable to a procedure which populates the result set by using a select statement.

  PROCEDURE  get_cust_bystate ( var_state_code in varchar, var_ref_cursor in out cust_data_cursor );
End customer_info;
 

Creating Package Body
Create or replace package body customer_info as
  PROCEDURE get_cust_by_state ( var_state_code in varchar, var_ref_cursor in out cust_data_cursor ) is
  begin
       Open cust_data_cursor FOR
            Select * from customer where state_code = var_state_code;
  Exception
      When others then
        Raise_Application_Error ( -20001, 'Error while executing get_cust_by_state in customer_info package ');
  End  get_cust_by_state;
End customer_info;