1. Banking: Borrowing from bank A to pay off bank B and then borrowing from bank C to pay off bank A ... and so on without ever paying off the originally borrowed principal. This scheme collapses when interest payments become too large for the debtor, resulting in bankruptcy if a debt consolidation is not arranged.
2. Corporate: Taking control of a firm (subsidiary) through majority shareholding and then taking control of another firm with the combined shareholding ... and so on to build a large holding company that provides managerial and financial (and sometimes marketing) functions for the entire group.
3. Finance: Using paper profits to build up a portfolio of investments.
4. Real estate: Purchasing additional properties by borrowing against the currently owned properties.