On Wednesday Mozilla released Firefox with Bing, a customized version of the browser that makes Bing.com the default homepage and sets Bing as the default search engine. The offering extends the partnership Mozilla and Microsoft announced last year.

"There are nearly 20 customized versions of Firefox distributed globally by partners including Bing, United Internet, Twitter, Yahoo! and Yandex," Mozilla said in a blog post.

Of course, any user of Firefox can go into the browser's settings and make those changes themselves if they want, and there is even a "Bing Search for Firefox" add-on that will do the same.

Google competes with Bing on the search side and Google's Chrome browser competes with Firefox. Microsoft makes a Firefox rival in Internet Explorer.