Sibling comments have good answers about the definition, but just to clarify the motivation a bit, the typical justification I've heard for mandatory parking sp

Sibling comments have good answers about the definition, but just to clarify the motivation a bit, the typical justification I've heard for mandatory parking spaces is to avoid a prisoner's dilemma between building owners, especially when there's street parking in the area. Let's say you have 10 buildings in an area, all of which provide some parking, plus there's some street parking. Any one of those buildings could decide to convert its parking into more homes or stores or whatever would make them more money, and just tell their customers/residents to use the other parking nearby. If everyone did this, nobody would have anywhere to park (especially not visitors), and building owners would have relatively little incentive to provide their own parking (they don't want to be the sucker). By forcing everyone to provide some amount of parking, you're overriding the bad incentives and getting people to cooperate for the greater good. At least theoretically, it's a good example of the government stepping in and making things better for everyone. I think that rationale holds up less well with dedicated parking, pay-to-park, and parking garages, but certainly there are areas where free parking is the norm. That's the theory (I think), though it has plenty of downsides. I'm not interested in owning a car, so the last four places I've lived have provided a parking space that went unused, and have had absurdly high rents due to the Bay Area's housing shortage (which might be alleviated by replacing parking spaces with housing).