Americans feel that physical contact can be important in breaking down
barriers between people. Such physical acts as hugging, shaking hands
and kissing in public are seen as displays of affection.
In China, on the other hand, this is not common because physical contact
is not the custom. Interestingly enough, most Chinese who spend some
time in America come to like hugging; they learn that Americans use
body language to express feelings. It is a way of saying "I like you and I
care about you."
Shaking hands is another traditional way of greeting someone in
America. Shaking hands is a more formal way of greeting than hugging.
Whereas hugging shows closeness, shaking hands means that there is a
little more formality in the relationship.
Western people usually shake hands when meeting someone for the first
time, or when they see someone again after a certain amount of time has
passed. In Japan, people traditionally bow as a form of greeting. Other
countries have different customs, like patting someone on the back or
kissing.