Why did the ww1 start?

The assassination of Franz Ferdinand was merely the spark that set off the war. World War I's causes were many. Some of these include colonial disputes, disputes in the Balkan nations, the decline of imperial powers, and an arms/technology race that resulted from the Industrial Revolution.

Well, one of the biggest and most well known causes for the start of World War I was the assassination of Archduke Ferdinand of Austria. This caused a lot of diplomatic and political tension among the different countries of Europe because of their respective alliances.