Among PPC providers, Google Ads (formerly Google AdWords), Microsoft adCenter and Yahoo! Search Marketing had been the three largest network operators, all three operating under a bid-based model. For example, in the year 2014, PPC(Adwords) or online advertising attributed approximately US$45 billion of the total US$66 billion of Google's annual revenue In 2010, Yahoo and Microsoft launched their combined effort against Google, and Microsoft's Bing began to be the search engine that Yahoo used to provide its search results. Since they joined forces, their PPC platform was renamed AdCenter. Their combined network of third party sites that allow AdCenter ads to populate banner and text ads on their site is called BingAds.