Why do people laugh?

A person might ask: what causes laughter?  Why do people laugh?  Why does your body react the way it does when you're being tickled, and how come you can't tickle yourself?  What emotions trigger our bodies to dive into a condition of uncontrollable hysterics?  There are seven types of humor, but there are even more types of laughter.  Whether you're confused, nervous, or happy, laughing can always seem like a solution.

On the subject of the cause of laughter, the answer isn't a simple one.  It depends.  Laughter is categorized in three ways.  The first instance: a person telling a joke, cracking a smile that soon turns into an insane path of laughter.  The second instance: a person that feigns a soft chuckle, either from embarrassment or pretending to be amused at a joke that they don't find all that funny.  The third instance: someone being tickled, choking on gasps of laughter.  So, ultimately, there is laughter caused from amusement, fake laughter, and laughter caused from someone being tickled.  Multiple different types of laughter can fall into each group.

What is the difference between these three different categories of laughter?  Aren't they all the same thing?

First, I'll delve into the category that seems to get the least amount of attention, and for good reason.  Feigned laughter.  It can almost always be spotted when it occurs, despite how convincing of an actor the sound is coming from.  People may imitate laughter for a variety of different reasons, including being distracted from the topic of conversation (or just not in the mood) but not wanting to stand out by being the only one not laughing at a joke, embarrassment, or from being nervous.

Oppositely, laughter caused from happiness or amusement is completely genuine and extremely difficult to fake.  This particular type of laughter, sometimes known as "happy laughter" or "hysterical laughter", can be triggered from intense emotions ranging from amusement to satisfaction to confusion to relief.  Regardless of the reason, it is typically a pleasant sound and elicits smiles or similar laughter from people around the room.

Laughter from being tickled might be a completely different experience than amused laughter to some people.  It might bring a smile to your face, but not necessarily a smile of happiness.  Many people hate being tickled, and for good reason.  The act of tickling triggers a sensation that activates part of the brain that copes with pain.  Have you ever wondered why we have certain "ticklish" spots on our bodies?  If you notice, most people are ticklish in their weakest spots, such as their feet, neck, or stomach.  This results in our "fight or flight" mechanism being triggered, leading to what we know as ticklish laughter.  Unlike genuinely funny laughter, tickling causes the hypothalamus - which controls instinctive reactions (think fight or flight) - to activate.  The hypothalamus also controls body temperature, hunger, and tiredness.  Some people start to laugh at merely the mention of being tickled.  In someone being tickled, their unmyelinated nerve fibers that cause pain are being stimulated.  This is the reason why people are known to lash out at their attacker when being tickled.  This also explains why you can't tickle yourself; your brain is aware that there is no need to produce a response to the action because it knows you don't need protection and aren't in any danger.  Tickling may be playful to some people, but to others is can just be painful.

So, those are the three categories and a basic summary of what they entail.  The causes and triggers of laughter have been listed and details about each category of laughter have been explained.  Next time you want to get even with an enemy, who would have thought tickling would be an option?