Zynga Inc is a US-based company that develops, markets, and operates social games as live services played on mobile platforms, such as iOS and Android, and social networking sites, such as Facebook. Zynga generates revenue through mobile game downloads, in-games sales of virtual goods, and advertising services. Zynga's revenue is divided between Online game and Advertising and other, where Online game accounts for the vast majority of total revenue. The firm's top three games account for the majority of its online game revenue. The company invests in several game categories, such as Social Casino, including Zynga Poker; Casual, including Words With Friends; Action Strategy, including Empires & Allies; and Invest Express, including Farmville.