Red is a color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometers and is a primary color in the RGB color model and a secondary color (made from magenta and yellow) in the CMYK color model. Reds range from the brilliant yellow-tinged scarlet and vermillion to bluish-red crimson, and vary in shade from the pale red pink to the dark red burgundy. Red is also the international color of stop signs and stop lights on highways and intersections.

In addition to being a color, "Red" is also the name of a division of The ONE Campaign, a global movement campaigning to end extreme poverty and preventable disease by 2030. (RED) partners with the world’s most iconic brands and organizations to develop (RED)-branded products and experiences that, when purchased, trigger corporate giving to the Global Fund to fight AIDS and the inequities that allow it to thrive. As of December 2021, (RED) has generated over US$750 million to support Global Fund grants for HIV and AIDS programs in Ghana, Eswatini, Kenya, Lesotho, Rwanda, South Africa, Tanzania, and Zambia.