Sole E25 Elliptical, blue

Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The term blue generally describes colours perceived by humans observing light with a dominant wavelength that's between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called the Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective.

Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultramarine, the most expensive of all pigments. In the eighth century Chinese artists used cobalt blue to colour fine blue and white porcelain. In the Middle Ages, European artists used it in the windows of cathedrals. Europeans wore clothing coloured with the vegetable dye woad until it was replaced by the finer indigo from America. In the 19th century, synthetic blue dyes and pigments gradually replaced organic dyes and mineral pigments. Dark blue became a common colour for military uniforms and later, in the late 20th century, for business suits. Because blue has commonly been associated with harmony, it was chosen as the colour of the flags of the United Nations and the European Union.

In the United States and Europe, blue is the colour that both men and women are most likely to choose as their favourite, with at least one recent survey showing the same across several other countries, including China, Malaysia, and Indonesia. Past surveys in the US and Europe have found that blue is the colour most commonly associated with harmony, confidence, masculinity, knowledge, intelligence, calmness, distance, infinity, the imagination, cold, and sadness.

E25 or E-25 may refer to:

• E25 fuel, see Common ethanol fuel mixtures
• European route E25, a road connecting Hook of Holland in the Netherlands and Palermo in Italy
• A German World War II tank version, see Entwicklung series#JagdpanzerE-25
• A variant of the Nissan Caravan produced from 2001-2012
• Meihan Expressway and Nishi-Meihan Expressway, route E25 in Japan
• Kuala Lumpur–Kuala Selangor Expressway, route E25 in Malaysia
• Ecuador Highway 25 or E25, Troncal de la Costa (Coastal Trunk) which goes from San Miguel de los Bancos through Guayaquil to Peru

Elliptical may mean:

• having the shape of an ellipse, or more broadly, any oval shape
  • in botany, having an elliptic leaf shape
  • of aircraft wings, having an elliptical planform
• characterised by ellipsis (the omission of words), or by concision more broadly
• elliptical trainer, an exercise machine