A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, face, head, vocal folds, trunk, and legs. Most tremors occur in the hands. In some people, a tremor is a symptom of another neurological disorder. A very common tremor is the teeth chattering, usually induced by cold temperatures or by fear. Types
Tremor is most commonly classified by clinical features and cause or origin. Some of the better-known forms of tremor, with their symptoms, include the following:

Cerebellar tremor (also known as intention tremor) is a slow, broad tremor of the extremities that occurs at the end of a purposeful movement, such as trying to press a button or touching a finger to the tip of ones nose. Cerebellar tremor is caused by lesions in or damage to the cerebellum resulting from stroke, tumor, or disease such as multiple sclerosis or some inherited degenerative disorder. It can also result from chronic alcoholism or overuse of some medicines. In classic cerebellar tremor, a lesion on one side of the brain produces a tremor in that same side of the body that worsens with directed movement. Cerebellar damage can also produce a "wing-beating" type of tremor called rubral or Holmes tremor — a combination of rest, action, and postural tremors. The tremor is often most prominent when the affected person is active or is maintaining a particular posture.
The tremor can then be classified by which position most accentuates the tremor:

Treatment
There is no cure for most tremors. The appropriate treatment depends on accurate diagnosis of the cause. Some tremors respond to treatment of the underlying condition. For example, in some cases of psychogenic tremor, treating the patients underlying psychological problem may cause the tremor to disappear. A few medications can help relieve symptoms temporarily. Medications
Medications remain the basis of therapy in many cases. Symptomatic drug therapy is available for several forms of tremor:
Parkinsonian tremor drug treatment involves L-DOPA or dopamine-like drugs such as pergolide, bromocriptine and ropinirole; They can be dangerous, however, as they may cause symptoms such as tardive dyskinesia, akathisia, clonus, and in rare instances tardive (late developing) psychosis. Other drugs used to lessen parkinsonian tremor include amantadine and anticholinergic drugs like benztropine
Essential tremor may be treated with beta blockers (such as propranolol and nadolol) or  primidone, an anticonvulsant
Cerebellar tremor symptoms may decrease with the application of alcohol (ethanol) or benzodiazepine medications, both of which carry some risk of dependence or addiction
Rubral tremor patients may receive some relief using L-DOPA or anticholinergic drugs. Surgery may be helpful
Dystonic tremor may respond to diazepam, anticholinergic drugs, and intramuscular injections of botulinum toxin. Botulinum toxin is also prescribed to treat voice and head tremors and several movement disorders
Primary orthostatic tremor sometimes is treated with a combination of diazepam and primidone. Gabapentin provides relief in some cases
Enhanced physiological tremor is usually reversible once the cause is corrected.