Euclid of Alexandria

Euclid
Euclid by Justus van Gent, 15th century
Born	Mid-4th century BCE
Died	Mid-3rd century BCE
Residence	Alexandria, Hellenistic Egypt
Fields	Mathematics
Known for	Euclidean geometry Euclid's Elements Euclidean algorithm

Euclid (/ˈjuːklᵻd/; Greek: , Eukleidēs Ancient Greek: [eu̯.klěː.dɛːs]; fl. 300 BCE), sometimes called Euclid of Alexandria to distinguish him from Euclides of Megara, was a Greek mathematician, often referred to as the "father of geometry". He was active in Alexandria during the reign of Ptolemy I (323–283 BCE). His Elements is one of the most influential works in the history of mathematics, serving as the main textbook for teaching mathematics (especially geometry) from the time of its publication until the late 19th or early 20th century. In the Elements, Euclid deduced the principles of what is now called Euclidean geometry from a small set of axioms. Euclid also wrote works on perspective, conic sections, spherical geometry, number theory and rigor.

Euclid is the anglicized version of the Greek name Εὐκλείδης, which means "renowned, glorious".

Very few original references to Euclid survive, so little is known about his life. The date, place and circumstances of both his birth and death are unknown and may only be estimated roughly relative to other people mentioned with him. He is rarely mentioned by name by other Greek mathematicians from Archimedes (c. 287 BC – c. 212 BC) onward, and is usually referred to as "ὁ στοιχειώτης" ("the author of Elements"). The few historical references to Euclid were written centuries after he lived by Proclus c. 450 AD and Pappus of Alexandria c. 320 AD.