No single extinguisher can be used to tackle every fire, and because each type of fire extinguisher has different categories of fire on which it is effective, selection can be a minefield.
The first step is to look at what materials are present in the area to be protected from fire. These can be divided into six fire classes involving different substances:

Class A fire caused by combustible carbon-based solids such as paper, wood or textiles
Class B fire caused by flammable liquids eg paraffin, petrol, diesel or oil (but not cooking oil)
Class C fire caused by flammable gases, eg butane, propane or methane
Class D fire caused by burning metals, eg aluminium, lithium or magnesium
Fires caused by electrical equipment (indicated by an electric spark symbol and not the letter E)
Class F fire caused by fats and cooking oils.
Five main types of fire extinguishers
There are five different fire extinguishers, which are: