Answer:
Allies were Britain, France and Russia, while Central Powers were Germany, Austria-Hungary and Italy. During the WW1 things changed as Italy decided to support Allies and United States also entered the war on their side. Ottoman Empire and Bulgaria supported Central Powers.
Step-by-step explanation:
This military alliances were created at the end of 19th and beginning of 20th Century. Animosity eventually led to beginning of WW1. Main reason for their animosity was the distribution of colonial power.