A civil war is a war that is fought internally within a nation between differing factions, religious groups, or powers. Exactly what makes a war "civil" can be hard to pin down; one common definition includes several criteria, including when both sides in the dispute have gained control of territory, created their own governments — however marginal — and have some sort of organized military that performs regular operations. In addition, most people only consider a conflict a civil war when other nations recognize the claims of one or more parties in the conflict. Smaller or less widespread conflicts may be known as insurgencies or insurrections, although they certainly have the potential to develop into a war.
Many Americans think of the American Civil War when they hear the term, but in fact, civil wars have marked human societies for centuries. These wars between countrymen can be particularly destructive, because they undermine the infrastructure and confidence of a country. In some cases, such a war might restore the balance of power in a country, while in other instances it might result in a more oppressive government, depending on who ultimately wins the conflict.
Some people like to distinguish between this type of conflict and a revolution or insurrection, arguing that a civil war involves distinct powers or factions. This is in contrast to an insurrection, when ordinary citizens individually start banding together to oppose the government, usually because they perceive it as unjust. A large-scale insurrection may turn into a revolution, with a violent overthrow of a prevailing government in the interests of the people. In some cases, the aftermath of a revolution turns into a civil war, because various factions may have emerged among the rebels to struggle for power.
There are a wide range of reasons that a war within a country can begin, ranging from religious beliefs to conflicts over available resources. Civil wars can be rapid and extremely efficient, like coups, or they can stretch on for decades, often costing thousands of lives and totally disrupting society. In this case, outside governments may step in to stabilize the region, either because they are concerned about events in the country or they are dealing with an influx of refugees from the fighting.
Many nations all over the world have struggled with civil wars, from Asia to Latin America. In parts of Africa, these conflicts became endemic after the collapse of colonialism, and some endure to this day. Sadly, in some cases genocide has accompanied civil war, as was the case in Rwanda, and many wars also claim large numbers of uninvolved civilians as well.