Every element in Sn is a product of cycles. Even more is true:
Every permutation of Sn is a product of disjoint cycles. This product is unique up to rearrangement of the factors.
If a permutation is written as a product of disjoint cycles, we say that it is given in disjoint cycles form or disjoint cycles notation. 1-cycles are usually left out in this notation.
The above proposition justifies the following definition:
The cycle structure of a permutation g is the (unordered) sequence of the cycle lengths in an expression of g as a product of disjoint cycles.
So, rephrasing the above proposition, we can say that every permutation has a unique cycle structure.