The Internal Rate of Return (IRR) is the rate at which each invested dollar is projected to grow for each period it is invested. It differs from other metrics in that it accounts for the concept of the “time value of money”, or the fact that a dollar received and reinvested elsewhere today is worth more than a dollar expected to be received and reinvested next year. The IRR is one of the best ways for an investor to compare various investments based on their yield while holding other variables constant.