Herndon is a town in Fairfax County, Virginia, United States, part of the Washington, D.C., metropolitan area.

However, the United States Post Office treats nearby unincorporated communities in northwestern Fairfax County as part of a Greater Herndon region,[discuss] including Dranesville, Floris, Franklin Farm, McNair, and Oak Hill.

Commander Herndon captained the ill-fated steamer SS Central America, going down with his ship while helping to save over 150 of its passengers and crew.

In the 1870s, many Northern soldiers and their families came to settle in the area, taking advantage of moderate climate and low land prices.

[5] Originally part of the rural surroundings of the Washington, D.C. area, the town of Herndon developed into a hub of dairy farming and vacationing for area residents, aided by its presence along the Alexandria, Loudoun and Hampshire Railroad (later to become the Washington and Old Dominion (W&OD) Railroad).

[5] When the railroad was converted into a hike-and-bike trail, Herndon capitalized on history and small-town feel (in a major metropolitan region) by converting its train station into a museum and visitors center and by relocating a Norfolk Southern Railway caboose to a nearby site and repainting it in W&OD livery.

[7][6] Although the caboose itself never traveled through Herndon, it remains an iconic part of the downtown area that both locals and tourists visit daily.

[6] The caboose and station offer a glimpse of the original downtown's historic charm, which residents are passionate about preserving.

[8] The town of Herndon was part of a nationally reported controversy involving illegal immigration beginning in 2005.

[10] The HOW Center was created on March 23, 2006, in response to daily gatherings of Hispanic workers at a local 7-Eleven store.

[13] According to the United States Census Bureau, the town has a total area of 4.2 square miles (10.9 km2), all of it land.

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, Stride, Inc., 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.

Others have Herndon mailing addresses but are located in unincorporated Fairfax or Loudoun counties; for example, south of the Dulles Toll Road.

The climate in this area is characterized by hot, humid summers and generally mild to cool winters.