Leonhard Euler was a Swiss mathematician and physicist born in 1707 in Basel, Switzerland. He made seminal contributions to many areas of mathematics and physics. Some of his most notable work included introducing mathematical notation still used today like π and the letter e, developing calculus through his work with power series and integrals, and solving problems in graph theory and number theory. In physics and astronomy, he made important discoveries applying calculus to problems involving mechanics, optics, and celestial motions. Despite losing his sight later in life, Euler continued his prolific work, writing on topics across mathematics, physics, and other fields until his death in 1783 in Saint Petersburg, Russia.