The traditional form of greeting, showing respect, saying thanks or saying goodbye in Asia is to slightly bow, often with the hands in prayer position at the heart level. Each culture or country has their particular nuance.
Shaking hands is a very unsanitary practice. People cough and sneeze in those hands. They eat chips, candy, fries, sandwiches, etc. and merely wipe them with a napkin when finished. Who knows what other unsanitary practices are down with those hands before shaking someone else's?
I wonder how we could get Americans to adopt this practice instead of shaking hands? I wonder if the number of people contracting the flu and colds would go down?