Nyon derives from one of the names used by the Romans for the town, Noviodunum or Noiodunum. Other names for the town, particularly of colonies placed there, are Colonia Iulia Equestris or Colonia Julia Equestris, Colonia

Nyon is first mentioned around 367–407 as civitas Equestrium id est Noiodunus (in the "Notitia Galliarum"). In 1236, it was mentioned as Neveduni and in 1292 as Nyons.

Nyon has an area, as of 2009 , of 6.8 square kilometers (2.6 sq mi). Of this area, 2.66 km (1.03 sq mi) or 39.2% is used for agricultural purposes, while 0.53 km (0.20 sq mi) or 7.8% is forested. Of the rest of the land, 3.67 km (1.42 sq mi) or 54.1% is settled (buildings or

Nyon has a population (as of December 2020 ) of 21,718. As of 2008 , 38.0% of the population are resident foreign nationals. Over the last 10 years (1999–2009) the population has changed at

Nyon has a high school (Gymnase de Nyon, known as CESSOuest until 1997 or 1998), a modern hospital, a movie theater, numerous hotels, restaurants, and cafes. The town is well known on the international stage as the home of the headquarters for

The blazon of the municipal coat of arms is Per pale Gules and Azure, overall a Fish nainaint Argent.

Nyon Castle and the Museum of the History of Porcelain, the Roman Colonia Iulia Equestris, the Swiss Reformed Church of Notre-Dame, the Manoir at Rue Maupertuis 2 & 4, the