Gottfried Wilhelm Leibniz, a German philosopher and mathematician, made groundbreaking contributions to calculus, philosophy, and logic. Independently of Newton, he developed calculus and introduced the integral (∫) and differential (d) notation still used today. Despite a historic controversy over calculus's invention, Leibniz's system proved elegant and practical. Beyond mathematics, his philosophical work in Monadology explored a universe governed by rational principles, and he envisioned a universal logical language, influencing symbolic logic and modern computation. Leibniz also designed the "Step Reckoner," an early mechanical calculator. His visionary ideas laid the foundation for advancements in mathematics, logic, and computer science, securing his legacy as one of history's greatest thinkers.