What is essential tremor?

Hand tremor: Essential means that there is no known cause.

Tremor of aging: It can occur in the wrists/hands or the head and neck (think of kaltheryn hepburn). Although it can cause a lot of problems for patients, it is not associated with a disease that effects someone's lifespan (such as parkinson's). It occurs when one holds the arms out and some with movement, but goes away when resting & supported. (parkinson's tremor is mostly seen when resting & supported.).