What did Euclid do?

Euclid (circa 300 BCE) was an ancient Greek mathematician best known for his monumental work, the Elements, which is one of the most influential works in the history of mathematics.

The Elements: This was a 13-volume treatise that systematically compiled and organized the geometric and number theory knowledge of his time.
It established a rigorous logical framework for geometry based on definitions, postulates (axioms), and theorems that were proven deductively from these foundations.
It covered plane geometry (properties of triangles, circles, parallel lines), solid geometry (properties of three-dimensional figures like spheres and polyhedra), and number theory (including concepts like prime numbers and perfect numbers).

Father of Geometry: Because of the Elements, Euclid is widely known as the "father of geometry." His axiomatic approach became the standard for mathematical reasoning for over two millennia.

Influence: The Elements was the primary textbook for teaching mathematics from its writing until the late 19th or early 20th century. Its emphasis on proof and logical structure profoundly shaped Western thought and the development of science.

Other Works: While the Elements is his most famous, Euclid also wrote other works on topics like optics, conic sections, and spherical geometry, though some of these are lost or less well-known.

Euclid's primary contribution was compiling existing geometric and number theory knowledge into a single, logically coherent framework in his work, the Elements. This established the axiomatic method and served as the foundational text for mathematics education for over 2000 years.