Let us also understand the classes of fires.
Class A
These are fires that involve some solid material like, clothers, paper, junk-heap, wood etc.
Class B
These are fires that involve liquid materials like: petrol, gasoline, diesel, oil etc.
Class C
These are fires that involve electrical elements
Class D
These are fires are those involve metals
Its important to know about the classes of fires because fire-extinguishers are classified and marked based on the type of fire on which they would be effective.
So, in case of a fire, you first want to know the Class of fire, so that you can use the right extinguishers.
If you use the wrong extinguisher(s), the result could be fatal also in some cases. In best case situation, there would be no injury etc. but, you could still loose precious time – in performing an activity which is useless.