What are violent conflicts and war?

A very general definition that most scientists will probably agree on is the following: War is a dispute between two or more organised groups, fought with systematic violence that lasts for a longer period of time. In the early 19th and 20th century, war was an armed conflict that follows the formal declaration of war by a state against another and that was decided in a final battle: the victor was able to enforce his will against the looser.

Today, there is hardly any formal declaration of war. Indeed, states are often involved, but are rarely the only relevant violent actors. And indeed, in some present day wars no state actor is directly involved and violent conflicts disregard any geographical and chronological boundaries. Today, so-called asymmetric wars, which are violent conflicts between two radically unequal opponents (unequal in the sense of their capacities and resources) are becoming more and more prominent.