When choosing a fire extinguisher, the first thing you need to know is that there are varieties of fire extinguishers available for different fire classes
1.ABC Powder Type Fire Extinguisher
2.DCP Powder Type Fire Extinguisher
3.Carbon Dioxide (CO2) Type Fire Extinguisher
4.Mechanical Foam Type Fire Extinguisher
5.Water Type Fire Extinguisher
6.Modular Fire Extinguisher (Automatic Roof Unit)
7.Class-K type fire extinguisher (wet chemical)
8.Clean agent fire extinguisher

which extinguishers used for each classes

There is no one extinguisher type which works on all classes of fire.
You will also need to make sure that you have the right size and weight of fire extinguisher as well as the right kind.

1)Class A fires:Powder,foam, Water, or wet chemical extinguishers
2)Class B fires:Powder,Foam, or carbon dioxide (CO2) extinguishers
3)Class C fires: Powder or carbon dioxide (CO2) extinguishers
4)Class D fires: Specialized powder extinguishers designed for metal fires
5)Electrical fires: Powder,CO2, or wet chemical extinguishers (Note: Water-based extinguishers should be avoided for electrical fires)
6)Class F fires: Wet chemical extinguishers
The various types of fire extinguisher put out fires started with different types of fuel – these are called ‘classes’ of fire. The fire risk from the different classes of fire in your home or your business premises will determine which fire extinguisher types you need.