Euclid is known as the "Father of Geometry." He was an ancient Greek mathematician active in Alexandria around 300 BCE. His most famous work, "Elements," is a compilation of knowledge that laid the groundwork for modern mathematics and geometry. In "Elements," Euclid introduced a systematic approach to geometry based on definitions, postulates, and logical deductions. His work defined various geometric concepts, such as points, lines, angles, and shapes, establishing principles that are still taught in geometry classes today. Euclid's influence extends beyond mathematics, impacting philosophy, logic, and the development of rigorous mathematical proof.