Click to see VDO of Thai greeting 
When you arrive to Thailand. First thing if you notice is Thai way of greeting.In Thai we say ” wai ไหว้ “ . This is one of Thai culture greeting you should know. (click to read more article about “wai”
When people are greeting each other they will say “SA-WAD-DEE สวัสดี” It can translate as Hello. You can say “SA-WAD-DEE สวัสดี” anytime when you meet any Thais.
It doesn’t matter if you meet in the morning ,afternoon or evening.You can add the word ” Ka ค่ะ” (female speaker) or “krab ครับ (male speaker)
female : “sa-wad-dee ka” สวัสดีค่ะ
male : “sa-wad-dee krab” สวัสดีครับ