A CAGR (Compound Annual Growth Rate) measures the rate of return of an investment over a period of time as if it had grown at a steady consistent rate on an annually compounded basis. So it measures the year-over-year growth rate of an investment over a specified period of time.
Example :
If you invest an amount of Rs 10,000/- and after two years you get back Rs 20,000/-, the CAGR will be 42.42%.