WWI - Write about the progression of WWI

In the year or 1914, tragedy struck. Millions lost their lives in the ordeal and cost billions. What was this tragic event? It was World War I, which lasted approximately 4-5 years. Why is it called a World War? There were many countries involved, which caused devastating effects. There are many causes that may have lead to it, but there are several specific factors.
<Tab/>One factor that may have caused World War I was the Alliance System. First of all, there was the central-power which included Germany and Austria-Hungary and the Triple Entente which included France, Russia…