What is "unearned increment"

Unearned \Un*earned"\, a. Not earned; not gained by labor or service.

Unearned increment (Polit. Econ.), a increase in the value of land due to no labor or expenditure on the part of the owner, but to natural causes, such as the increase of population, the growth of a town in the vicinity, or the like. Some hold that this should belong to the nation.

n. an unearned rise in the market value of property resulting from general market factors

Unearned increment is an increase in the value of land or any property without expenditure of any kind on the part of the proprietor; it is an early statement of the notion of unearned income. It was coined by John Stuart Mill, who proposed taxing it. Mill's concept was refined and developed by nineteenth-century economist Henry George in his book Progress and Poverty (1879).