Definition of 'Folio Number'
In mutual funds, a unique number identifying your account with the fund. Like a bank account number, the folio number can be used as a way to uniquely identify fund investors and keep records of items such as how much money each investor has placed with the fund, their transaction history and contact details.
A folio number can also be used to identify journal entries or parcels of land.
Investopedia explains 'Folio Number'
All mutual funds need some sort of recordkeeping system in place. This information is necessary for ensuring each investor is returned the money they are entitled to, and for determining what fee structure applies to each investor. While recordkeeping is most often facilitated by the broker, in some cases an investor may be asked for a folio number by the fund provider to help ensure accuracy. This folio number may be present on investment statements or may be obtained through your broker.