The document discusses capital structure concepts and theories. It defines capital structure as the mix of owned and borrowed capital used to finance a firm's assets. There are several theories that attempt to explain the relationship between capital structure, cost of capital, and firm value. The Net Income approach suggests firm value increases as debt rises since interest is tax deductible. The Net Operating Income approach argues firm value is independent of capital structure. Modigliani-Miller's theory also initially supports this, but recognizes value increases with debt when taxes are considered. The Traditional approach finds an optimal capital structure that minimizes the weighted average cost of capital and maximizes firm value.