Red is the color at the end of low frequency in the visible spectrum of electromagnetic waves, and its frequency range is 380 ~ 480 Hz, corresponding to the wavelength of 780 ~ 620 nm in the air. Red is one of the three primary colors and four psychological colors of light, which is similar to the color of fresh blood. The optical complementary color of red is cyan, while red and green are a pair of contrasting colors. Red is one of the three primary colors of light. It can be mixed with turquoise and indigo to produce any color. Red represents positive optimism and enthusiasm, and the mood fluctuates greatly; Sincere and proactive, joking regardless of occasion; Dare to challenge, eager to do something vigorous; Good at expressing and neglecting to fulfill promises; It's contagious. This mountain looks higher than that one.