Cursor is a pointer to a PRIVATE work area , which contains data or information retrieved with SQL statements( a dataset encapsulated within a system defined memory space) . Cursors are automatically generated by Oracle utilities like SQL*Plus.
Oracle Holds SQL statements in a SHARED SQL AREA.Please refer to this document,  dynviews_2108.htm , for the details about the SQL SHARED MEMORY used with CURSOR.

 

 

There are four steps to rollup a cursor, DECLARE, OPEN, FETCH AND CLOSE the cursors.
An Implicit cursor is the one, which is created "automatically" as one query is executed. An implicit cursor is generated de novo with a DML statement with INSERT, UPDATE OR DELETE  clauses. The most recent implicit cursors can be handled with 5FOUND, %ISOPEN, %NOTFOUND  and %ROWFOUND . An explicit cursor is created by the user by writing codes with PL/SQL

Explicit cursor tender more dynamic and manageable  programmatically .

A demo PL/SQL Cursor Script:

declare
 cursor emp_cur is    select c   from emp
   order by sal DESC;
 var_name VARCHAR2 (10);
 var_empno NUMBER (4);
 var_sal NUMBER (7,2);
BEGIN
  OPEN  emp_cur;
  for i in 1..5 LOOP
  fetch emp_cur INTO var_name, var_empno, var_sal;
 EXIT WHEN emp_cur%notfound;
dbms_output.put_line (var_name||var_empno||','||var_sal);
end loop;
close emp_cur;
end;
/
 
I shall post some examples, later , in this series of documents.
Note: I would like to add few lines about retrieving Cursor variables into a Visual Studio Recordset; scope of OLE-DB is huge at this juncture.