How To Greet
When Laotians greet each other, they press the palms of their hands in together with their fingers pointing upwards as if in prayer and this is called "vai". Thais also greet the same way but they call it "wai". A vai is a way to show respect to the other person
and you can do it while you're standing, sitting or walking, it doesn't really matter.
Lao and Thai culture is different when it comes to greeting someone with a vai, and you will see people vai more often in Thailand than in Laos. In Thai culture, the Thais greet all the time whenever they meet each other such as every day at work or whenever they visit someones place which I think is too over the top.
Thais also vai to each other when they are leaving, I've also seen Thai friends vai to each other where as in Lao culture we do not do this.
In Lao culture, we only vai depending on the situation and status of the person. A junior (younger) person vais to the senior (older) person only when the junior person meets the senior person for the first time, or when the junior person has not seen the older person for a long time.
Sometimes the senior person returns the vai to the junior person and sometimes they do not but this is not a sign of disrespect,
but it is disrespectful if the junior person does not vai.
A senior person should also vai to a senior person if they meet for the first time, or if they haven't seen each other for a long time but there are exceptions. For example if both senior people are friends then they don't need to vai to each other. If both senior people are relatives then they don't need to vai to each other. If both senior people are guys and they meet each other for the first time then they can handshake instead of vai.
Senior and junior people can only vai to a Lao woman and never give her a handshake. If you meet a Lao woman on your first date, it is not necessary to vai to her regardless of her age but it is not wrong to do it. If you meet her parents for the first time then you should vai to them if they look older than you.
Here is an example scenario. A 35 year old Lao person name Toui meets an elderly 70 year old Lao person for the first time.
Toui should vai to the elderly person but the elderly person doesn't have to vai back. Toui meets the elderly person again the next day, in this case Toui doesn't need to vai to the elderly person. Toui meets the elderly person again in 6 months time, in this case Toui should vai to the elderly person.
Another example scenario. A 24 year old Lao woman meets a 27 year old Lao woman for the first time, it is not necessary for either of them to vai but just a simple "hello" is fine. If this was Thai culture, both Thai women would vai to each other which is abit funny.
Another example scenario. A 24 year old Lao guy meets a 27 year old Lao guy for the first time, it is not necessary for either of them to vai but they should give each other a handshake and say hello, similar to western culture.
I hope our explanation made sense to you about vai, the traditional form of greeting in Lao culture.