Balance of power refers to the counterbalance of power between nations. It is the distribution of power in which no single nation is able to dominate or interfere with.
In international relations, nations seek to maintain an approximate equilibrium of power among many rivals, thus preventing the preponderance of any one state. For maintaining balance of power there must be willingness on the part of individual national governments to change alliances as the situation demands. Balance of power exists when there is parity or stability between competing forces.