Funds are financial instruments invested by investors and managed by professional institutions. It is based on investors' funds and is organized in the form of an investment portfolio to achieve the investor's investment goals. Funds of funds refer to funds in which fund investors invest, rather than other financial instruments in which investors invest.

Fund investors can invest in a variety of funds, including stock funds, bond funds, hybrid funds, index funds, money market funds, etc. Stock funds mainly invest in stocks, bond funds mainly invest in bonds, hybrid funds can invest in both stocks and bonds, index funds invest in index constituent stocks, and money market funds invest in money market instruments.

When investors invest in funds, in addition to the fund's investment portfolio, they must also consider the fund's income, risk level, expenses, etc. Investors can choose a fund that suits them from a variety of funds based on their investment goals and risk tolerance.

Fund investors should also pay attention to the fund's management agency. The more experienced and powerful the fund's management agency is, the higher the fund's investment income will be. Therefore, when choosing a fund, investors should carefully study the fund's management agency and choose a reputable management agency to ensure investment returns.

In addition, investors should also pay attention to fund expenses. Fund expenses include issuance fees, management fees, custody fees, etc., which will affect the fund's income. Therefore, when choosing a fund, investors should carefully study the fund's fees and choose funds with lower fees to obtain higher investment returns.

In short, the fund of funds is the fund that investors invest in. When choosing a fund, investors must carefully study the fund's investment portfolio, income, risk level, expenses, etc. to ensure investment returns. In addition, investors should also pay attention to the fund's management organization and fees to ensure investment safety.