If F is an algebraic Galois extension field of K such that the Galois group of the extension is Abelian, then F is said to be an Abelian extension of K. For example, Q(sqrt(2)) = {a + bsqrt(2)} is the field of rational numbers with the square root of two adjoined, a degree-two extension of Q. Its Galois group has two elements, the nontrivial element sending sqrt(2) to -sqrt(2), and is Abelian.

algebraic extension | cyclotomic field | extension field | fundamental theorem of Galois theory | Galois extension field | Galois group | number field