Official Answer: 
--The following is from about.com's article: What Is Stimming and Why Is It Common In Autistic People?--

The term "stimming" is short for self-stimulatory behavior, sometimes also called "stereotypic" behavior. In a person with autism, stimming usually refers to specific behaviors such as flapping, rocking, spinning, or repetition of words and phrases. 

Stimming is almost always a symptom of autism, but it's important to note that stimming is also a part of most people's behavior patterns. If you've ever tapped your pencil, bitten your nails, twirled your hair, or paced, you've engaged in stimming.

The biggest differences between autistic and typical stimming are the choice of stim and the quantity of stim. 


While it's at least moderately acceptable to bite one's nails, for example, it's considered unacceptable to wander around flapping one's hands. There's really no good reason why flapping should be less acceptable than nail biting (it's certainly more hygienic!). But in our world, the hand flappers receive negative attention while the nail biters are tolerated.
Like anyone else, people with autism stim to help themselves to manage anxiety, fear, anger, and other negative emotions.


To read more about stimming, click here.

To read my addition to this blog, click here:
Stimming Helpers