Red is the hottest of the warm colors (this palette contains also yellow, orange, brown, gold). There are 25 shades of red, from Alizarin to Vermilion.

In many cultures red symbolizes power, hence the red carpet for celebrities and VIPs.

In China red is the color of happiness and prosperity, it is used to attract good luck and is worn by the brides. Money in Chinese societies is traditionally given in red envelopes.

In South Africa, however, red is the colour of mourning. Red is considered holy in some parts of sub-Sahara Africa, and women in these regions are forbidden to wear red clothes.

Studies show that red has stimulating effect; it can increase the rate of respiration and raise blood pressure. Red may cause restlessness and insomnia when used in bedrooms, but it is considered appropriate for exercise and play rooms. In addition, red, along with yellow and orange, is thought to provoke hunger.

Lesser sensitivity to red light than normal is called protanomaly. It is a fairly rare form of color blindness, making up about 1% of the male population.

Red is the color most commonly found in national flags.