👉 A backset is a set of all elements that are common to two or more sets. It is often used in mathematics and computer science, particularly when dealing with sets and their operations. Backsets can be defined for any binary relation on a set S, such as an order relation or a subset relation. In the context of backsets, we refer to elements that appear in both sides of the relation (i.e., they are common to all elements in one side and not common to all elements