It’s the phrase guaranteed to garner applause in mayoral stump speeches. It’s in surveys year after year. It’s the subject of a $20 billion bond Bay Area voters will decide on in November.

Affordable housing. But what does the phrase actually mean? The term is often used for any housing with rent or price restrictions — paying no more than 30% of your gross income toward housing is considered “affordable,” by federal standards. But even within that definition, there are several types of affordable housing, and not all with the same requirements around income and rent.

Most funds to build affordable housing directly subsidize the building itself. Only renters with qualifying incomes may apply to the units. In some cases, the government develops and owns housing complexes it rents out at below-market rates.

The units are controlled by local housing authorities, which are governed independently from the cities where they provide housing and primarily funded by the U.S. Department of Housing and Urban Development (HUD).

The 372-unit Lockwood Gardens in Oakland and the 300-unit Corde Terra apartments in San Jose are two examples of public housing built by local housing authorities. Because of local housing authorities’ dependence on HUD for funding, some housing advocates say California should create its own public housing authority. Last year, both chambers of the state legislature passed a bill to create a California Housing Authority, charged with building mixed-i.