Who were the slavs and what did they have to do with World War I?

Answer: Slavs are an ethnic and linguistic branch of European peoples who live in central and eastern Europe and the Balkans. World War I was started because of the assassination of Archduke Franz Ferdinand of Austro-Hungary by a south Slavic nationalist named Gavrilo Princip. If you think about it, without this assassination there would have been no WWI and thus no WWII and thus probably no Vietnam or Korean War or Cold War or Persian Gulf War, etc.