The term "Pythagorean" primarily refers to the ancient Greek mathematician Pythagoras, who is best known for his contributions to mathematics, particularly in geometry. The most famous concept associated with him is the Pythagorean theorem, which states that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides. This theorem is fundamental in various fields, including architecture, engineering, and physics. In addition to mathematics, the Pythagorean school, founded by Pythagoras, also explored philosophy, music, and the relationship between numbers and the universe. Pythagoreans believed that numbers had mystical properties and that understanding them could lead to a deeper understanding of reality. Their ideas laid the groundwork for later developments in mathematics and science.