EURORDIS, a European alliance of rare disease patient organizations, launched Rare Disease Day in 2008. Its inaugural edition fell on February 29 — the rarest date on the calendar, occurring only once every four years — symbolizing the rarity of the diseases themselves. Since then, it has been observed annually on the last day of February, whether that is the 28th or the 29th. A disease is typically classified as “rare” if it affects fewer than 1 in 2,000 people, yet the total number of people living with a rare disease is estimated at more than 300 million worldwide, across an estimated 6,000 to 8,000 known rare diseases, many of them genetic and apparent from childhood. Patients often face significant challenges, including delayed diagnosis, scarce specialized treatments, high treatment costs, and, at times, limited awareness even among physicians. The day is marked in more than 100 countries through awareness events organized by patient associations and hospitals, advocacy campaigns pushing for better health policies, and the sharing of patient and family stories to break the isolation many feel due to the rarity of their condition.