What were the new technologies used in world war i? how did they change the nature of warfare?

There were many technological changes during WWI in regards to military technology. These included developments in tanks, airplanes, ships, flamethrowers, and other weapons. But two of the most important developments were the use of chemical weapons and also the machine gun. The machine gun especially led to the development of trench warfare in WWI because mobile weapons did not advance as much as stationary machine guns and artillery which led to large stalemates in terms of obtaining territory and instead each side sought to dig in and defend their territories through trench warfare. 

Italy , germany, austria, japan, and brazil.