Gestures are forms of non-verbal communication. Through certain body moves we send messages to other people. Gestures can be performed together with words or without them. Gestures differ from culture to culture.
In India people traditionally grasp their earlobes as an expression of remorse or honesty. In Saudi Arabia a person "says" yes by shaking his head from side to side. For Egyptians it is very rude to show a sole of your shoe.
Thumbs up is in many cultures seen as something positive. Iran is an exception. There it is treated as vulgar. In Mexico be careful when holding hands on your hips. It may be seen as an hostile act. In Vietnam avoiding eye contact is a way to show respect to older people, people of higher social status and persons of opposite sex.