Wars are large-scale conflicts between groups, typically nations or states, involving organized military forces. These conflicts arise from disputes over various issues, such as territory, resources, power, ideology, or religious beliefs. Wars often result in significant destruction, loss of life, and long-term societal and economic impacts.

There are different types of wars, including:

1. "Civil Wars": Conflicts within a single country, often between different groups, factions, or regions.
2. "World Wars": Large-scale conflicts that involve multiple nations across the globe, such as World War I and World War II.
3. "Revolutionary Wars": Wars fought to overthrow a government or political system, often led by revolutionary movements.
4. "Proxy Wars": Conflicts where two opposing countries or groups support combatants that serve their interests rather than directly engaging in the conflict themselves.
5. "Guerrilla Wars": Conflicts characterized by small, mobile groups of combatants using irregular tactics to fight larger, more traditional military forces.

Wars can have various causes, including political, economic, social, and cultural factors, and they often have lasting consequences on the societies involved.