The document discusses capital structure and the advantages and disadvantages of debt versus equity financing. It summarizes Modigliani and Miller's seminal work which established that in a perfect capital market without taxes, a firm's value is independent of its capital structure. When taxes are considered, debt provides a tax shield that increases firm value up to a point, after which additional debt increases financial distress costs. The optimal capital structure balances the tax benefits of debt against the costs of financial distress.