Euclid was an ancient Greek mathematician, often referred to as the 'Father of Geometry.' He is best known for his work, Elements, which systematically compiled and organized the knowledge of geometry of his time. This influential text laid the groundwork for modern mathematics and introduced concepts such as points, lines, and planes. In Elements, Euclid presented definitions, postulates, and proofs that are still taught in geometry classes today. His logical approach to mathematics emphasized the importance of deductive reasoning, making his work a cornerstone of mathematical education for centuries.