prayer flags...

"...are so name because on each flag, there is scripture. Waving in the wind, they are also called wind flags. To the believers, each waving of the flag means reciting the scripture once, sending wishes of sentient beings to the deities. In this way, the prayer-flags serve as a connection between human being and the deities. They also believe that the deities are just behind the flags, listening to their prayers. (...) The five colors of the flags stand for different meanings. Blue is for sky, white for cloud, red for flame, green for water and yellow for earth. So the blue flag must be hung above, while the yellow one below to strictly follow the universal order." text from: "Tibetan Customs" - Li Tao & Jiang Hong Ying, China Intercontinental Press