According to the GAAFR (the Blue Book), governmental funds are “used to account for activities primarily supported by taxes, grants, and similar revenue sources.” Within the category of Governmental Funds, there are five types: General Fund, special revenue funds, debt service funds, capital projects funds, and permanent funds.
While there is only one General Fund, which is the primary operating fund, there can be several of each of the other types of governmental funds. For example, you may have multiple special revenue funds for specific revenue sources that are restricted for specific purposes: State Street Aid Fund, Drug Fund, etc. You also may have multiple debt service funds, such as those that account for long-term debt: General Obligation Bond Fund, General Debt Service Fund, etc.
Likewise, the city may have multiple capital projects funds that are set aside for acquisition and/or construction of capital facilities and other capital assets: City Hall Capital Project Fund, Fire Truck Capital Project Fund, Ballpark Improvement Fund, etc. Finally, there can be multiple permanent funds: Cemetery Perpetual Care Fund and School Endowment Fund, for example.