There are several main fire extinguisher agents, namely water, foam, Co2, powder and wet chemical.
Each of the different types of fire extinguisher agents are suitable for different fire classes:
Water: Suitable for Class A fires.
AFFF Foam: Suitable for Class A and B fires.
CO2: Suitable for Class B and C fires.
ABC and BC Powder: Most versatile and can be used on Class A, B, C
Wet Chemical: Designed specifically for use on Class F (deep fat) fires, and sometimes class A.