The following are equivalent definitions for a Galois extension field (also simply known as a Galois extension) K of F. 1.K is the splitting field for a collection of separable polynomials. When K is a finite extension, then only one separable polynomial is necessary. 2. The field automorphisms of K that fix F do not fix any intermediate fields E, i.e., F subset E subset K. 3. Every irreducible polynomial over F which has a root in K factors into linear factors in K. Also, K must be a separable extension.