If the Great War of 1914 was a conflict between mainly European nations, why would historians refer to it as a world war?  How was the rest of the world affected?

spanish executed counts egmont and horne in brussels.

i think i will need more detail to answer if this is a specific question on a test, but technology advancements are good for many industries, such as medicine or food industries, new technology could us in medicine in ways such as new scanners to tell us more about our bodies or new cures or vaccines for diseases.