A "format war" is when two or more companies or groups are competing with each other to establish their own specific way of doing something as the new standard, while trying to eliminate or replace the existing way. Full definition
As we moved into the current generation of gaming we saw the media format war pan out in the early life cycle of the PS3 and Xbox 360. (thatvideogameblog.com)
Like the rest of the gadget world, e-readers are in the midst of their own format war. (gizmodo.com)
Whether or not that is a problem will be decided whenever that quiet format war winds down. (tomsguide.com)