Since red is the color of blood, it has historically been associated with sacrifice, danger and courage.
Modern surveys in the United States and Europe show red is also the color most commonly associated with heat, activity, passion, sexuality, anger, love and joy. In China, India and many other Asian countries it is the color of symbolizing happiness and good fortune. In the United States, red pertains to the Republican Party and its supporters, as in Red states and blue states.
Red is also a color widely used for getting attention, such as stop signs or royal dresses, and is associated with socialism and communism, like the flag of the Soviet Union or People's Republic of China