Changed my mind. This is my new favorite description:

What is Tremor?


Tremor refers to rhythmic shaking of a body part. There are more than 20 kinds of tremor. Essential Tremor (ET) is the most common. Although called benign essential tremor in the past, it may be far from benign. It may be frustrating, embarrassing, or disabling. People with ET may avoid dining in restaurants or talking in front of others. They may be tired of being told they're "nervous" because their voice quivers or they fear the ordeal of signing a check in public.


Essential tremor is a very common and complex neurologic movement disorder. It is not caused by another neurological condition or the side effect of a medication. ET usually affects the hands, but it may also affect the head and neck (causing shaking), face, jaw, tongue, voice (causing a shaking or quivering sound), the trunk and, rarely, the legs and feet. The tremor may be a rhythmic "back-and-forth" or "to-and-fro" movement produced by involuntary contractions of the muscle. Severity of the tremors can vary greatly from hour to hour and day to day.


Some people experience tremor only in certain positions – this is called postural tremor. Tremor that worsens while writing or eating is called kinetic or action-specific tremor. Most people with ET have both postural and kinetic tremor.