Capital structure is the mix of debt and equity financing a company uses to fund operations and growth. This unit explores key theories like Modigliani-Miller, trade-off, and pecking order, which explain how firms choose their optimal financing mix. Companies balance the benefits of debt, such as tax advantages, against costs like financial distress. Factors influencing capital structure decisions include industry norms, growth stage, profitability, and market conditions. Real-world examples illustrate how firms apply these concepts in practice.