What made world war ll a total war?

A "total war" is when military force is used to destroy the country's economy and basic productivity, not just the opposing military forces.

In World War II, things like unrestricted submarine warfare in which the submarine was more likely to sink a cargo vessel than another warship, or aerial bombardment of industrial facilities weren't designed to kill the enemy soldiers; they were designed to cripple the entire nation. German submarines aimed to cripple England by cutting off the flow of raw materials transported by cargo ships. The US Navy did the same thing, more successfully, to Japan. German aircraft dropped explosive bombs on cities rather than on military targets, and British and American bombers responded in kind.