Edited sentence: An important, but fairly old aspect of the theory is the classification of finite fields :.Any two finite fields with the same order are isomorphic.For every prime number p and positive integer n, there exists a finite field with pn elements.The order or number of elements of a finite field equals pn, where p is a prime number called the characteristic of the field, and n is a positive integer.The theory of finite fields is perhaps the most important aspect of finite ring theory due to its intimate connections with algebraic geometry, Galois theory and number theory