The theory of the sets —taken to its ultimate expression by the German mathematician Georg Cantor— was the one that allowed a new expanded vision of the concept of infinity. The new infinity is based on the most basic concept of cardinality.
On this issue of cardinality and its implications for the new idea of infinity, there are several resources on this website.
But before we get to the ideas of Cantor's evolution and refinement, it is necessary to review the basics of sets, what are they, and the subsets derived from of the sets.
This infographic is a summary of the essential concepts of sets, subsets, and cardinality, and the intimate relationship between them.
For the PDF version of this infographic follow this link.
For the image jpg version of this infographic follow this link.