The custom of saying a hand came to us from ancient Rome. So the soldiers showed. That they are without weapons. About handshake, you can make a preliminary opinion about an unfamiliar person, about his attitude towards you:
If greeting a person, you notice that he, when shaking, turns your hand a little, most likely he wants to show his dominant position and the further conversation will prefer to conduct himself.
The approach of a person during the handshake also speaks of claims to leadership.
If, instead of a brush, a person tries to (rather mechanically) to shake your wrist, he is tuned in a combat. And if you have a lot of controversial questions, it is better to postpone the conversation for a while.
If a person with a handshake touches your forearm, then he experiences friendly feelings for you.
Someone is too very shakes your hand – he is aggressively and obviously not happy with something. The hand served directly, without bending the elbow, also testifies to the aggressive mood.
Handsome is a very useful, especially in business negotiations, tradition, paying such a seemingly little attention, how many useful attention can be extracted.