Civilian control of the military is a doctrine in military and political science that places ultimate responsibility for a country's strategic decision-making in the hands of the civilian political leadership, rather than professional military officers.
In reality, most countries do not have perfect civilian control over the military. However, in countries with strong civil-military control, civilian governments exercise sufficient oversight that they are able to control the majority of military decisions.
Countries with weak civil-military control often see the military able to exercise significant autonomy over society, including but not limited to expanding their corporate and political interests, and carrying out military operations without oversight from the government.