Parkinson's disease begins inconspicuously and progresses gradually. There are two main categories of symptoms in Parkinson's disease: motor symptoms and non-motor symptoms. In the early stages of the disease, one can appear normal, or may experience motor symptoms like bradykinesia or rigidity, often starting asymmetrically. Symptoms commonly begin on one side of the upper limbs, and less frequently start from the lower limbs, eventually spreading to the limbs on the other side. Non-motor symptoms can occur at various stages of Parkinson's disease, including the pre-motor phase, such as loss of smell, sleep disturbances, constipation, depression, and more.