Euclid (pronounced EWK-lid) was an ancient Greek mathematician who lived around 300 BC.

He is considered the father of geometry. He worked in Alexandria during the reign of the great king, Ptolemy I (323–283 BC).

Euclid's most famous writings are called "The Elements." It is among the most influential works in the history of mathematics. "The Elements" served as the textbook for teaching mathematics for most of the recorded history of the planet, from 300 BC until the early 20th century. His theories developed so long ago infulenced the development of mathematics for more than 2,000 years.