Most extinguishers are either powder (Aluminum Phosphate) or carbon dioxide filled.
They have A, B, C ratings - the higher the rating, the better...
A is for ordinary combustible materials - paper, wood, fabrics - things that are quenched by using water or powder
B is for flammable liquids - gasoline, grease, oil, paint - things that powder or carbon dioxide put out. Never use water.
C is for live electrical - appliances, electrical outlets - use powder or carbon dioxide. Never use water.
Powder is a good all-around extinguisher - the problem is it is very messy. If you use powder on an engine fire, be prepared to spend many hours cleaning the stuff off.