Canon is the annual fee paid for the use of land that is not privately owned but issued in leasehold (erfpacht), usually by the municipality. In Amsterdam, this fee is typically paid to the city and is tax-deductible, much like mortgage interest.
There is also private leasehold (particuliere erfpacht), where the land is owned by a private individual or entity instead of the municipality. Properties under private leasehold are more difficult to finance, and their resale value may be negatively affected due to the legal complexity and potential uncertainty around future ground rent terms.