There are 5 main types of extinguishers

WATER

Used for class A Risk : Wood , Paper, Textiles etc.

FOAM (AFFF)

Used for class A Risk as above and also for

Class B Flammable Liquids.

POWDER

Used for Mixed Risk Class A and Class B and also safe on electrical risk

CARBON DIOXIDE

Used for Electrical Risk and small Class B

WET CHEMICAL

Used for Class F Risk Deep Fat Fryers

There are advantages and disadvantages with most extinguishers therefore advice is best sought before any purchases