The buttons are part of a new feature Google has introduced in its AdSense program, which shares revenue with Web site operators that agree to carry advertising from Google. AdSense Referral is for site publishers looking to make money by using Google-provided buttons linking to products and services.
Google has had a close relationship with Mozilla for sometime. Firefox ships with Google search built into the browser. The latest deal expands that relationship by getting the browser on Google's huge ad network.
Firefox competes with Microsoft Corp.'s Internet Explorer, which dominates the browser market. Microsoft and Google are fierce rivals. Microsoft, which considers the search engines a key competitor, is making a major push in the growing online advertising market where Google and Yahoo Inc. have earned billions of dollars.