Why did warfare in the 20th century result in significantly higher casualties than in previous conflicts?

Warfare in the 20th century resulted in significantly higher casualties than in previous conflicts due to advancements in technology, such as more powerful weapons like machine guns, tanks, and aircraft, as well as the use of chemical weapons and strategic bombing. These innovations made it easier to kill large numbers of people quickly and from a distance, leading to higher casualty rates in battles and wars.