The war that broke out in Europe in 1914 and involved the major countries of Europe became known as World War I largely because some combat occurred outside the main European battlefields. But this name is a bit of a misnomer. The main combatants stayed the same and to the extent that the war was fought outside of Europe it was because battles were fought in the far flung empires of Britain and Germany. British and German forces fought in Africa and in Australasia but these were largely battles between British and German forces. Further, the war was world wide in scope because technology and communications allowed greater expansion of belligerence than had been possible before. The next decade marks the hundredth anniversary of The Great War. Typically, in matters philatelic, centenary anniversaries mark an increase in collecting interest and I would expect this to be no different. WWI created hundreds of issues and scores of new stamp issuing entities. If any of these areas are within your collecting purview, now would be a good time to buy some of these stamps as prices will probably go up.