Many students or teachers ask themselves: Being given a natural number n, how many non-isomorphic groups of order n exists? The answer, generally, is not yet given. But, for certain values of the number n have answered this question. The present work gives a method to determine of all non-isomorphic groups of order 16 and gives descriptions of all these groups. The results obtained here can be used by students in the senior year, students in courses or seminars, or other Mathematics teachers are in different stages of their professional development.