In this episode, we explore the Internal Rate of Return (IRR), a fundamental method for calculating an investment's profitability by finding the interest rate that sets the Net Present Value (NPV) of cash flows to zero. We discuss why corporate executives often prefer IRR over NPV for comparing capital projects, even though maximizing NPV is generally preferred for increasing total value. The conversation covers practical applications, ranging from capital budgeting and stock buybacks to assessing private equity performance. We also examine critical limitations, including the "reinvestment debate," the mathematical anomaly of "multiple IRRs" when cash flow signs alternate, and how survivorship bias can inflate reported returns in private equity. Finally, we touch on alternatives designed to address these flaws, such as the Modified Internal Rate of Return (MIRR).