Fire extinguishers are devices commonly found indoors and are used to douse fire and prevent its spread. They are small metal canisters that contain compressed gas (usually nitrogen) that, when activated, propel a directed spray of flame-retardant chemicals. Fire extinguishers are only effective if building occupants understand where and why they are used.
Check out these resources to find out more about how to properly maintain, check and use a fire extinguisher in your home or office.
International Association of Certified Home Inspectors
http://www.nachi.org/fire-extinguisher-maintenance-inspection.htm
National Fire Protection Association
http://www.nfpa.org/safety-information/for-consumers/fire-and-safety-equipment/fire-extinguishers