CoStar Group, Inc. is a leading provider of online real estate marketplaces, information, and analytics in the U.S. and U.K. The company's core business model revolves around owning and operating online marketplaces for commercial real estate and apartment listings, with primary revenue streams coming from subscription-based services and advertising. CoStar differentiates itself through its comprehensive database, research capabilities, and technology, serving a broad range of industry professionals and consumers.