Technology had a major impact on the way that World War I (WWI) was fought and somewhat of an impact on the result of the war. Technology helped turn WWI into a war (at least on the Western Front) of murderous trench warfare. Eventually, though, technology in the form of tanks helped to break up the stalemate.
Two major new technologies were machine guns and rapid-fire artillery. These inventions made it much easier for an army to fight defensive battles. Because armies became so adept at defending, it was very hard for attacking armies to break through defensive lines. This meant that WWI became a stalemate that was fought between entrenched armies. The machine guns and artillery wreaked a horrible toll on soldiers who tried to attack entrenched enemy positions.
With the stalemate, armies turned to poison gas to try to gain an advantage. This was another new technology that made the trench warfare in WWI so murderous and so horrible for the soldiers. However, the poison gas did not really do anything to help determine the outcome of the war.
The only technology that had a major impact on the result of the war was the tank. Tanks helped break through the stalemate on the Western Front. Eventually, tanks helped the Allies defeat the Central Power. They are the only technology that had an important impact on who won the war.
U-boats were a deciding factor of World War I. If the Germans did not introduce submarine warfare, then it is very probable that the Unites States would not have entered the war, and thus it is possible that the war would have ended in the Central Powers' favor.
Another technology used was the telegram. This allowed for quicker communication for battle commands. Without them, the war would have been more unorganized and slower.
Other technologies like the machine gun and artillery gun allowed for easier defense; poison gas, torpedoes etc. allowed for swifter offense.