In mathematics, particularly in abstract algebra and homological algebra, the concept of projective module over a ring R is a generalisation of the idea of a free module (that is, a module with basis vectors). Various equivalent characterizations of these modules appear below.
Projective modules were first introduced in 1956 in the influential book Homological Algebra by Henri Cartan and Samuel Eilenberg.
Read more about Projective Module: Properties, Projective Resolutions, Projective Modules Over Commutative Rings, Vector Bundles and Locally Free Modules, Projective Modules Over A Polynomial Ring