What is parkinson's disease? what are the causes of the disease?

Too complex to elaborate here. Briefly, Parkinson's is a classic movement disorder, associated with resting tremor, unstable gait, stiffness, rigidity, problems swallowing, constipation, Lewy Body dementia, etc. Some causes include prior encephalitis, strokes, trauma, carbon monoxide, hypoxia, manganese toxicity, Paraquat, etc. Mayo Clinic or Johns Hopkins sites will add information.