What is the purpose of Humor or Laughter?
It is very difficult to define humour or how it functions. First of all you need wit (cognitive experience) for good humour, then amusement/irony (emotional experience) and laughter (physiological experience).
Laughter is often linked to humor, however, you will find that nervousness, tickling etc. does not have much to do with humor. The opposite holds also true where you have an instance of Humor without laughter. This may be because of social context or just the mood the “receiver” can be in. An example of such an instance can be when a person is experiencing stress, tension or fatigue with a sense of hopelessness – it is difficult to experience these feelings together with humor.

The act of laughter is also a very complex phenomenon. Laughter differs from standard speech in many ways. Laughter consists of a very wide variety of anatomical sources, more so than average speech. Laughter also occurs at a much higher pitch than everyday speech, where men often laughs within the vocal range of a female soprano singer! This is not always the case as laughter can also be expressed in grunts, giggles, chuckles and song-like sounds.

Humor can help us in many ways, it can replace distressing emotions with pleasurable feelings, soften the meaning so that the event is not that powerful and reduce stress by facilitating a shift in perspective.
As the old saying goes - Laughter is the best medicine!