CoStar Group, Inc. engages in the provision of online real estate marketplaces, information, and analytics in the commercial and residential property markets. It operates through the following segments: CoStar Portfolio, Information Services Portfolio, Multifamily Portfolio, LoopNet Portfolio, and Other Marketplaces Portfolio. The CoStar Portfolio segment consists of two classes of trade receivables based on geographical location: North America and International. The Information Services Portfolio segment includes four classes of trade receivables: CoStar Real Estate Manager, Hospitality, North America, Hospitality, International, and other Information Services. The Multifamily Portfolio, LoopNet Portfolio, and Other Marketplaces Portfolio segments focus on one class of trade receivables. The company was founded by Andrew C. Florance and Michael R. Klein in 1987 and is headquartered in Arlington, VA.