Wai is a graceful gesture that do when they greet each other. In doing so,the head is slightly bowed and palms pressed together at chest level.Thais people do the Wai when they want to greet, to say goodbye,to thank or to a pologize to other people They also say an expression along with the gesture suchas "Sawasdee"(hello) When they greet someone or "Khob Khun"(thank you) When they thank someone.