The costs of the war include 9 million soldiers, sailors, and airmen killed and 6 million civilians killed during Europe's four years of murderous insanity. The fighting cost the combatant nations about $180,000,000,000 in 1918 money. The Ottoman and Austrian-Hungarian empires disappeared forever, and the Russian empire was replaced by the Communist Soviet Union.
While today marks an ending, of sorts, of World War 1, we do well to remember how the war began. Capt. Edmund Blackadder explains the origins of the war in this clip from Blackadder Goes Forth(yes, that is Hugh Laurie).