Laughter is a voice expression (written ha ha ha), or is a reflection of joy or happiness, or in the feelings of cheerfulness and pressure. It is the result of (in the action of the psychological) of jokes, tickling and other simultaneous. A wide laugh can bring tears or even moderate pain.
Laughter is part of normal human behavior that results from the brain and can help humans in clearing the atmosphere in social life and can reflect emotions in conversation.
But not infrequently laughter is a way to cover up the deep sadness, which can not be revealed. Laughter in 10 minutes can burn 1000 calories.
