Green is the color between cyan and yellow in the visible spectrum. It is caused by light having a dominant wavelength of around 495-570 nm. In subtractive color systems used in color painting and printing, it is created by a combination of yellow and cyan. In the RGB color model used on television and computer displays, it is one of the additive primary colors, along with red and blue, that mix in various combinations to make all other colors. By far the biggest contributor to greenery in nature is chlorophyll, the chemical plants use to photosynthesise and convert sunlight into chemical energy. Many creatures have adapted to their green surroundings by adopting a shade of green as camouflage. Several minerals are green in color, including emerald, which is green in color due to its chromium content. During post-classical and early modern Europe, green was the color commonly associated with wealth, merchants, bankers, and the nobility, while red was reserved for the nobility. That’s why the costume of Leonardo da Vinci’s Mona Lisa and the benches of the British House of Commons are green, while those of the House of Lords are red. It also has a long historical tradition as the color of Ireland and Gaelic culture. It is the historic color of Islam and represents the exuberant greenery of paradise. It was the color of Muhammad’s banner and is found on the flags of almost all Islamic countries. In surveys conducted in American, European and Islamic countries, green is the color most commonly associated with nature, life, health, youth, spring, hope and envy. In the European Union and the United States, green is also sometimes associated with toxicity and ill health, but in China and most of Asia, its associations as a symbol of fertility and good luck are very positive. Due to its connection with nature, it is the color of the environmental movement. Political groups working for environmental protection and social justice describe themselves as part of the green movement, some describe themselves as green parties. This has led to advertising campaigns similar to those of companies selling green or eco-friendly products. Green is also the traditional color of safety and permission; a green light means you can proceed, a green card means permanent residence in the United States.