They can be small but of such a crucial importance, as they are the first line of defense in case of any fire emergency. They are an integral part of the fire safety provisions in any building. Extinguishers are of different types, each with a specific use, therefore selecting an extinguisher for any of the type of fire, is important. The classes of fire are:
A - Ordinary Fires such as wood, paper, & cloth etc
B - Flammable liquids & gases such as fuel, paint, oil, & gasoline etc
C - Electrical Equipment
D - Metals such as magnesium, phosphorus, and titanium etc

Following are the categories of fire extinguishers in respect to different classes of fire.
Dry Chemical Powder (DCP): DCP can be used on all fire classes.
Water Store Pressure (WSP): This is basically used on class A fires.
Carbon Dioxide (CO2): This is specifically used on the fires due to electricity or electrical equipment.
Halotron: It is a clean agent and can be used on all fires.
Aqueous Film Forming Foam (AFFF): This is specifically used on class B fires.
Fire extinguishers are often kept in cabinets in order to keep them safe.