Rent control refers to laws or ordinances that set price controls on the renting of residential housing. It functions as a price ceiling. Rent control exists in approximately 40 countries around the world. Rent control laws vary from one country to another, and may vary from one jurisdiction to another within some countries Rent control should be a necessity by the State of California or all cities to protect the public and to prevent landlords from imposing rent increases that cause key workers or vulnerable people to leave an area. Maintaining a supply of affordable housing is believed to be essential to sustaining the local society. Homeowners who support rent control point to the neighborhood instability caused by high or frequent rent increases and the effect on schools, youth groups, and community organizations when tenants move more frequently.