It closely tracks the performance of an index, a commodity or a basket of assets. ETFs are traded at exchange just like a stock and provide returns that closely correspond to the total return of the securities included in their baskets. ETFs are available for all leading market index across the world such as S&P, NASDAQE, and FTSE.
ETFs can be a great way to diversify your investments.
If you want to learn more check out these resources: