When meeting people at the airport, most people smile and shake hands with people they meet. We know that a smile is usually a sign that people feel friendly and happy, what if we don't know who the new person is? What if we are not (introduce) by a friend? Sometimes people are dangerous and humans have to find ways to protect (themself). We have to make sure we can trust people we do not know, and we have to show that we are not dangerous, showing our hands means that we are not armed. In many cultures today, the Western custom of (shake) hands is used. We use our right hand, which is usually (strong) than the left one. If we are using our hand this way, it cannot be holding a knife or a gun. It shows that we can trust each other.
Not all cultures use the handshake, and people in many Asian cultures do not always touch another person. Japanese people might cover one hand with other hand, depending on they are greeting, bow (slight) or quite low. A Muslim will touch his heart, mouth and forehead (show) respect. They are all keeping their hands busy. In almost all cultures, to smile and show an open right hand (mean). "Welcome, you are safe with me."
