Cost of capital is the minimum return a company must earn to satisfy investors. It's crucial for making informed decisions about investments and project selection. Understanding this concept helps managers create value by choosing projects that exceed the cost of capital. The weighted average cost of capital (WACC) combines the costs of debt and equity financing. It's essential for business valuation, as it directly impacts the present value of future cash flows. Cost of capital varies across industries and companies based on risk profiles and capital structures.