The hallmarks of PD are the key pathological attributes and clinical manifestations that characterize the condition. These hallmarks encompass both the underlying molecular and cellular changes within the brain, such as dopaminergic neuron degeneration, α-synuclein pathology, and neuroinflammation, as well as the observable characteristic motor and nonmotor symptoms that define the clinical presentation of the disease. Understanding these hallmarks is crucial for elucidating disease mechanisms, developing diagnostic biomarkers, and identifying potential therapeutic targets for PD.