Explain implicit vs explicit cursors in PL/SQL

Any SELECT INTO, INSERT, UPDATE, DELETE or MERGE runs through an implicit cursor whose outcome you read via SQL%FOUND, SQL%NOTFOUND and SQL%ROWCOUNT immediately afterward. An explicit cursor is one you DECLARE with a name, then OPEN / FETCH / CLOSE (or drive with a cursor FOR loop) — needed for multi-row result sets, for passing a result set around as a cursor variable, or for row-by-row locking with FOR UPDATE. A cursor FOR loop over an explicit or inline cursor is the usual, safest choice.

BEGIN
  UPDATE employees SET salary = salary * 1.03 WHERE department_id = 10;
  DBMS_OUTPUT.PUT_LINE('implicit: ' || SQL%ROWCOUNT || ' rows updated');
END;
/

DECLARE
  CURSOR c_emp IS SELECT employee_id, last_name FROM employees WHERE rownum <= 5;
BEGIN
  FOR r IN c_emp LOOP        -- explicit cursor, cursor FOR loop
    DBMS_OUTPUT.PUT_LINE(r.employee_id || ' ' || r.last_name);
  END LOOP;
END;
/