This chapter aims to define the problem of insurgency, before discussing the reasons for relatively poor performance in COIN, and provides some guidance on good COIN practice. Global insurgent networks complicate the task of COIN campaigns, in that the latter must include operations at global, national, and even local levels. Political mobilisation is an essential ingredient of most insurgencies. Despite the significance of these nonviolent political activities, an insurgency also relies on the application and threat of violence. The population is usually of central importance to the outcome of an insurgency. Since insurgent groups normally begin their campaigns at a substantial disadvantage relative to government forces, they must compensate for this in some way. COIN is clearly a complex form of strategy, and the historical record serves merely to illustrate this point. For the population to be controlled and/or persuaded through good works, the government must ensure that it limits the influence of the insurgents.