21Vianet Group, Inc. provides carrier-neutral Internet data center services to Internet companies, government entities, blue-chip enterprises, and small-to mid-sized enterprises in the Peoples Republic of China. It offers hosting and related services to house servers and networking equipment in its data centers, and connects them through a data transmission network; and other hosting related value-added services. Its hosting and related services include managed hosting services that offer data center space to customers servers and networking equipment and provide tailored server administration services; and interconnectivity services that enable customers to connect their servers with Internet backbones and other networks through its border gateway protocol network or single-line, dual-line, or multiple-line network. Its hosting and related services also comprise content delivery network services that optimize the speed and security of data transmission; cloud services that enable businesses to run their applications over the Internet using its IT infrastructure; virtual private network services; and other value-added services, such as firewall, server load balancing, data backup and recovery, data center management, server management, and backup server services. In addition, the company provides traffic charts and analysis, gateway monitoring for servers, domain name system setup, defense mechanism against distributed denial of service attacks, basic setting of switches and routers, and virus protections; and managed network services consisting of hosting area network, route optimization, and last-mile wired broadband services. As of December 31, 2015, it operated 16 self-built and 69 partnered data centers located in approximately 30 cities in China with 23,556 cabinets. It has strategic partnerships with Microsoft Corporation and IBM. The company was founded in 1999 and is headquartered in Beijing, the Peoples Republic of China.