The form of warfare in which peoples with low technology fight against "official" armies. The term was coined during the Spanish Peninsular war - part of the campaign of Britain against Napoleon. Irregular bands of Spanish fighters attacked French occupation forces. In Spanish it meant "little war".

The term has also been applied to the campaign by which Vietnamese forces defeated the highly technological army of the United States. The forces in Iraq fighting against US and British occupation may also be an example.

Should it be applied to the forces associated with Osama bin Laden? He probably thinks so. What is the distinction between Guerrilla war and Terrorism? None. It depends which side the description is favouring. However guerrilla is the more neutral term.

One of the problems of the modern world is that this form of war is becoming both cheap and very effective, making it more important to have political and economic arrangements that prevent it occurring. These might include democracy and social justice.

This type of war was an important reason for the ending of the colonial European empires.