Classical results in Group theory

This paper discusses some basic properties of an algebra structure -- group in six sections. The content starts with basic operations of elements in a set and continues with an introduction of group concepts in sections 1 and 2. The review of basic operation in a set prepares important concepts that will be used later in group theory. Subgroups and cyclic groups are reviewed in Sections 3 and 4 to complete the introduction of one single group's property. Concrete examples and geometry visualizations are included to deepen the understanding of the abstract concept and to offer a direct intuition. Subgroup and cyclic groups are also related to basic number theory which is also discussed in the content. Homomorphism and Isomorphism are discussed in sections 5 and 6. These two concepts relate to two and more groups together, giving a mapping with a good property among two and more groups.