Despite the frequent clashes with Microsoft — including the role Google played in thwarting an attempted acquisition of Yahoo — Google has come out on top only in search and search advertising. But Google does not have to win the browser war. Strategically, opening yet another front against Microsoft forces it to divert resources to defend franchises.

Now, Chrome heightens the rivalry and marks a shift for Google, which has strongly backed Firefox, the open-source browser that has gained about a fifth of the market against the dominant Internet Explorer.

Google’s browser project has been under way for more than a year, a person close to the company said.

In a brief statement, Microsoft welcomed the new entry and expressed confidence that people would prefer Explorer, which is on every Windows PC sold.

Check out PCWorld's take on the soon-to-be-expected browser.

Here's Google's comic book version of the whys behind the Chrome launch. Anyone worried that Chrome will kill off Mozilla?

The Chrome download was available a little before 3 p.m. on the East Coast.