A wai is an Asian custom used in greeting others in some countries. When visiting Thailand, in business situations they normally shake hands. A proper traditional greeting is performing a wai.

You put your two hands together as if in prayer. You place the tips of your index and middle fingers (with the area between the index finger its second knuckle) to your face. Depending on who you are greeting, the position on your face shows your rank and age to the other person. An everyday wai is to place your fingertips at your mouth level. Greeting someone below your station usually would mean putting your fingertips to your chin, but I recmmend substituting the lip-level wai. Greeting an elder, someone well above your station, a monk or royalty requires putting your fingertips at forehead-level.

When your hands are properly placed, you bow from the waist. Proper etiquette requires the youngest to wai the oldest, or the lower ranked person to wai the highest first. The oldest and highest ranking person would then return the wai.

If you are travelling in Thailand, be prepared to use the wai to everyone you introduce yourself to, and do it first. Even in business, you can perform a wai and then follow it up with a handshake.