Maps are particularly crucial on mobile devices, where location-based services and ads have emerged as the pathway to making money. Google and Apple are not the only warriors in the fight. Amazon, Nokia, Microsoft, AOL and Yahoo are competing, too.

“If you own a mobile ecology, as Google does, the other mobile ecology owners are not going to allow you to own tons of data in their world,” said Scott Rafer, chief executive of Lumatic, which makes city map apps. “And so neither Apple nor Amazon were going to let Google know where every one of their users was at every time.”

Being kicked off the iPhone has potentially significant consequences for Google, whose Maps service earns more than half its traffic from mobile devices, and almost half of that mobile traffic has been from iPhone users. Apple’s move strikes at the heart of Google’s core business, search, because about 40 percent of mobile searches are for local places or things.

“Local is a huge thing for Google in terms of advertising dollars, and search is very tied to that,” said Barry Schwartz, an editor at Search Engine Land, an industry blog. “Knowing where you are, when you search for coffee, it can bring up local coffee shops and ads that are much more relevant for the user.”

Consumers are innocent bystanders of the brawl. IPhone users now have an extra step to download the YouTube app from the App Store and, so far, Google has given no indication that it will offer a maps app. Apple’s maps, meanwhile, are littered with flaws, some laughable, like a bridge that appears to collapse crossing the Tacoma Narrows Strait of Puget Sound.