Euclid's Elements

Euclid's "Elements" (sometimes: "The Elements", "Stoicheia") is a large set of math books about geometry, written by the ancient Greek mathematician known as Euclid (c.325 BC–265 BC) in Alexandria (Egypt) circa 300 BC. The set has 13 volumes, or sections, and has been printed often as 13 physical books (numbered I-XIII), rather than one large book. It has been translated into Latin, with the title "Euclidis Elementorum". It is the most famous mathematical text from ancient times.
Euclid collected together all that was known of geometry in his time. His "Elements" is the main source of ancient geometry. Textbooks based on Euclid have been used up to the present day. In the book, he starts out from a small set of axioms (that is, a group of things that everyone thinks are true). Euclid then shows the properties of geometric objects and of whole numbers, based on those axioms.
The "Elements" also includes works on perspective, conic sections, spherical geometry, and possibly quadric surfaces. Apart from geometry, the work also includes number theory. Euclid came up with the idea of "greatest common divisors". They were in his "Elements". The greatest common divisor of two numbers is the greatest number that can divide evenly into both of the two numbers.
The geometrical system described in the "Elements" was long known simply as "geometry" and was considered to be the only geometry possible. Today, that system is referred to as "Euclidean geometry", to distinguish it from other so-called "non-Euclidean geometries" which mathematicians discovered in the 19th century.
Added volumes XIV and XV.
Occasionally in ancient times, writings were attributed to celebrated authors but were not written by them. It is in this way that the apocryphal books XIV and XV of the Elements were sometimes included in the collection. The spurious Book XIV was probably written by Hypsicles on the basis of a treatise by Apollonius of Perga. The book continues Euclid's comparison of regular solids inscribed in spheres. The chief result is that the ratio of the surfaces of the dodecahedron and icosahedron inscribed in the same sphere is the same as the ratio of their volumes.
The spurious Book XV was probably written, at least in part, by Isidore of Miletus. This book covers topics such as counting the number of edges and solid angles in the regular solids, and finding the measure of dihedral angles of faces that meet at an edge.
Editions.
Currently in print.
"Euclid's Elements – All thirteen books in one volume", based on Heath's translation, Green Lion Press, .
"The Elements: Books I-XIII-Complete and Unabridged" (2006), translated by Sir Thomas Heath, Barnes &amp; Noble, .