1. A set is a collection of elements that share a common property. Sets can be empty, finite with a definite number of elements, or infinite with no end to their elements. 2. Elements within a set are represented visually using a Venn diagram, which shows the relationships between sets such as subsets, unions, and intersections. 3. There are specific symbols used to represent set relationships and operations such as subset, union, intersection, complement, and membership.