Sir Isaac Newton was an English mathematician, physicist, and astronomer who is widely recognised as one of the most influential scientists of all time. He made groundbreaking contributions to classical mechanics, optics, and calculus. Newton's laws of motion and universal gravitation are still used today in physics and engineering. He also developed a form of infinitesimal calculus, which is now known as Newtonian calculus. Newton is considered to be the father of modern science and is credited with laying the foundations for the scientific revolution.