Why do people usually wear white clothes in hot countries?

Answer 1

To keep the sun from burning them. Sun can dry out your body and deplete your fluids. I've heard that when bedouin tribes moved across the desert, they ate a big meal and put on their long "robes". This elevated their body core temperature and supposedly made them feel cooler on the outside.

Answer 2

When the light of the sun is reflected off of white, which keeps you cooler, while the light of the sun is absorbed by black, making you warmer and black clothing also helps in trapping your body heat in cold countries so that you don't feel cold.

Answer 3

White reflects the sun

Black/Dark colours absorb the sun