Herndon is a town in Fairfax County, Virginia, in the Washington, D.C. metropolitan area of the United States. The population was 23,292 at the 2010 census, which makes it the largest of three incorporated towns in the county.
Herndon is part of the Dulles Technology Corridor, which Fortune magazine named the "Netplex" because of the presence of the headquarters of such companies as AOL, XO Communications, Verizon Business (formerly MCI, formerly WorldCom, originally UUNET), and Network Solutions, which began as the INTERNIC – the registry where every domain name was once administered.
Some of those companies are within Herndon. Others have Herndon mailing addresses, but are located in unincorporated Fairfax or Loudoun counties; for example, south of the Dulles Toll Road. These include Deltek and K12.