Green is a color made by combining yellow and blue pigment. It is a primary color in light. Green is the color of many plants and living things.
In the poem "Nothing Gold Can Stay", Robert Frost wrote:
Nature's first green is gold, her hardest hue to hold.[1]
Green is also a term used to refer to environmentally friendly -- and typically inefficient -- products. So green energy could be hydroelectric for instance, instead of fossil fuels.
The color green corresponds to wavelengths of 520 nanometers to 565 nanometers in the electromagnetic spectrum.[2]