Tremor and Parkinson's disease are two completely different concepts. Tremor is not necessarily Parkinson's disease, and Parkinson's disease does not necessarily involve tremor. Tremor is just a clinical symptom that can appear in many diseases. In addition to Parkinson's disease, there are also some essential tremors which are genetic. Patients usually experience tremors in their hands when maintaining certain postures, and may also have head tremors. This is a relatively benign disease with a generally good prognosis. Additionally, patients with hyperthyroidism may also experience limb tremors, but this is not Parkinson's disease. Moreover, many patients with Parkinson's disease experience bradykinesia and rigidity, and might not necessarily have limb tremors. Therefore, these two concepts are different; tremor is not necessarily Parkinson's disease.