Wai is a form of Thai culture which

Wai is a form of Thai culture which represents various aspects of Thai honorific system. For example, wai shows Thai politeness, respect, honor, and friendship. Thais wai when greeting or leaving. Along with a wai, Thais usually say 'sawasdee,' which means 'hello' in English. The wai tradition has been succeeded to the present generation since Sukhotai Period, approximately A.D. 1238). Wai can also be used in articulating apology or gratitude. For these purposes, a person who wais usually says, 'khor-thod' or 'khob-khun,' respectively.