The world wars were two of the largest scale wars man has ever seen. They both lasted very long and many were killed. They were both extremely tragic and should not be forgotten.
We'll start with WWI. It started July 28 1914. It lasted four years and ended November 11 1918. Many people died during the war but the allies won. Several countries participated.
The causes of the war can be attributed to the acronym M.A.I.N. M stands for militarism. Militarism is when a country believes that their military should be the best and most powerful certain countries believed that other were growing their military too big. The A stands for alliances. Allies are countries that help each other in time of war. This contributed to the war because when one country attacks another each of their allies help. I stands for imperialism. Imperialism is when is when a country expresses it's power through military force. Citizens of the countries felt oppressed by imperial nations. Finally N for nationalism. Nationalism is extreme patriotism. This caused countries to compete to see who was the "best". Many would say that the "final blow" was the assassination of the Arch Duke. Most of Europe participated as well as the United States. The war resulted in an allied victory.
Now for WWII. It started on September 1 1939 and ended on September 2 1945. The causes of the second world war are similar to the first. Mainly militarism. Japan invading China as well as Germany invading Poland.
Nazi Germany was largely blamed for the war. This was because under Hitler's rule Germany attacked many countries and broke many treaties. They invaded Poland and attacked the Soviet Union after signing the non aggression pact. Nazi Germany essentially tried to take over Europe and then the rest of the world. The reason this became WWII is because if Germany took Europe they could take the world. Japan was also a massive threat. The Soviet Union defeated Germany and the United States defeated Japan. Countries like the US didn't want to be involved but had no choice. Mostly the same countries participated. The results were the same as the first war. The allies won.
To conclude, the allies won both wars. Germany was largely blamed for both. They were more blamed for the second one. The causes of the wars were similar but not exactly the same. The first ended with German surrender. The second ended with Japan and German surrender.