Generally speaking, the number of constituent stocks of a broad-based index is often large, the weight of a single stock is low, and the investment target is also wide. On the contrary, the narrow base index is suitable for irregular and non-directional investment with certain timing and fundamental judgment. Generally speaking, wide base and narrow base are actually a common name, which mainly refers to the difference in investment direction and scope. If investors want to enter the investment market, it is very necessary to know the broad-based and narrow-based indexes.