What was the technology used in WWII?
Technological advances made WWII unlike any war that had previously been fought. Existing technologies were refined, and entirely new weapons emerged as a result of technical advances. This answer focuses on three areas of advancement that revolutionized air, land, and naval warfare.
IN THE AIR
The airplane had been around since the turn of the century and had been used in combat in WWI, but WWII brought about technical advances and new uses for the airplane. As steel, mono-wing planes replaced wood and canvas biplanes, fighters became faster and bombers could fly farther to deliver larger bomb loads. These advances allowed strategic bombing to become an important tactic, especially for the allies against the Germans. The large bombers of the period could fly far enough behind enemy lines to attack population and industrial centers. This same long-range bombing technology allowed the United States to drop atomic bombs on Japan. WWII also brought about the first jet-powered airplanes.
ON THE GROUND
Tanks had been around in various forms since WWI, but it was during WWII that they became a major force on the battlefield. They became faster, more reliable, and more lethal so that by the 1930s, trench warfare had become obsolete. The German “blitzkrieg” or lightning war in Poland demonstrated how tanks, in conjunction with airplanes and infantry, could quickly defeat an unprepared nation.
In WWII, aircraft carriers became the most important ship in the navy, especially in the conflict between the United States and Japan in the Pacific. No longer tied to land bases, fighters and bombers could be brought to a battle along with traditional battleships, destroyers and submarines. This made for a whole new doctrine of naval warfare whereby traditional surface ships became less valuable because they were vulnerable to air attack.