World Parkinson's Day (WPD) is observed globally every year on 11 April to raise awareness about Parkinson’s disease (PD) — a chronic, progressive neurological disorder affecting both motor and non-motor functions. The date commemorates the birth anniversary of Dr. James Parkinson, the English surgeon who first described PD as "paralysis agitans" in his 1817 work An Essay on the Shaking Palsy.