Laughter

Laughing is an involuntary reaction to certain external or internal stimuli. Laughter can arise from such activities as being tickled,[1] or from humorous stories or thoughts.[2] Most commonly, it is considered a visual expression of a number of positive emotional states, such as joy, mirth, happiness, relief, etc. On some occasions, however, it may be caused by contrary emotional states such as embarrassment, apology, or confusion ("nervous laughter)" or courtesy laugh. Factors such as age, gender, education, language, and culture are determinant factors[3] as to whether a person will experience laughter in a given situation.
Laughter is a part of human behavior regulated by the brain, helping humans clarify their intentions in social interaction and providing an emotional context to conversations. Laughter is used as a signal for being part of a group — it signals acceptance and positive interactions with others. Laughter is sometimes seen as contagious, and the laughter of one person can itself provoke laughter from others as a positive feedback.[4] This may account in part for the popularity of laugh tracks in situation comedy television shows.
The study of humor and laughter, and its psychological and physiological effects on the human body, is called gelotology. laugh·ter [pic][pic] (l[pic]f[pic]t[pic]r, läf[pic]-)
n.
1. The act of laughing.
2. The sound produced by laughing.
3. Archaic A cause or subject for laughter

laughter [ˈlɑːftə] n 1. the action of or noise produced by laughing
2. the experience or manifestation of mirth, amusement, scorn, or joy

laugh•ter (ˈlæf tər, ˈlɑf-)

n.
1. the action or sound of laughing.
2. an experiencing of the emotion expressed by laughing.
3. an expression or appearance of merriment.
4. Archaic. an object of laughter.
Laughter is the Best Medicine[pic]
The Health Benefits of Humor and Laughter
[pic]

Humor is infectious. The sound of roaring laughter is far more contagious than any cough,