The Thai greeting referred to as the wai (Thai: ไหว้, pronounced [wâːj]) consists of a slight bow, with the palms pressed together in a prayer-like fashion. It is very similar to the Indian Añjali Mudrā/namasté and the Cambodian sampeah. The higher the hands are held in relation to the face and the lower the bow, the more respect or reverence the giver of the wai is showing.
The wai is also common as a way to thank someone or apologize.
The word often spoken with the wai as a greeting or farewell is sawasdee (สวัสดี, pronounced [sàwàtdiː]). This word was coined in the mid-1930s by Phraya Upakit Silapasan of Chulalongkorn University. This word, derived from the Sanskrit svasti (meaning “well-being”), had previously been used in Thai only as a formulaic opening to inscriptions. The strongly nationalist government of Plaek Pibulsonggram in the early 1940s promoted the use of the word sawasdee amongst the government bureaucracy as well as the wider populace as part of a wider set of cultural edicts to modernize Thailand.
(Thanks to Wikipedia for that info.)
I find this greeting very inviting and expressive. There are so many subtle variables (okay, some are not as subtle) that add intensity and enthusiasm or which express a sense of obligation only. Yes, it’s a bit formal feeling to those of us from the West where the greeting has all but faded from our vocabulary except in places where some sort of greeting has become a kind of brand expression. “Welcome to Moe’s.” Still, I like it.
Maybe it’s because the combination of both words and a gesture that requires both hands and a bit of a bow forces a pause and that pause offers opportunity to see people, to reflect on their presence. I’m sure you can do all of this it auto pilot as well as any ritual. I think that’s one of the benefits of experiencing other cultures and experimenting with other rituals.