Specific Effects of World War 1:
WW1 caused the downfall of four monarchies: Germany, Turkey, Austria-Hungary and Russia.
The war made people more open to other ideologies, such as the Bolsheviks that came to power in Russia and fascism that triumphed in Italy and even later in Germany.
WW1 largely marked the end of colonialism, as the people became more nationalistic and the one country after the other started colonial revolts in Southeast Asia, the Middle East and Africa.
The war changed the economical balance of the world, leaving European countries deep in debt and making the U.S. the leading industrial power and creditor in the world.
Inflation shot up in most countries and the German economy was highly affected by having to pay for reparations.
With troops travelling all over the world, influenza was spread easily and an epidemic started which killed more than 25 million people across the world.
With all the new weapons that were used, WW1 changed the face of modern warfare forever.
Due to the cruel methods used during the war and the losses suffered, WW1 caused a lot of bitterness among nations, which also greatly contributed to WW1 decades later.
Social life also changed: women had to run businesses while the men were at war and labor laws started to be enforced due to mass production and mechanization. People all wanted better living standards.
After WW1, the need for an international body of nations that promotes security and peace worldwide became evident. This caused the founding of the League of Nations.
WW1 boosted research in technology, because better transport and means of communication gave countries an advantage over their enemies.
The harsh conditions of the Treaty of Versailles caused a lot of dissent in Europe, especially on the side of the Central Powers who had to pay a lot for financial reparations.