An element of a set is any one of the distinct objects that belong to a set. For example given the set , one could say that is an element of the set .

Notation

To express that a given object is an element of a set the symbol is used. This relationship is called set membership. For example given the set stating that is an element of the set could be written as .

Alternatively, the negation of set membership expresses that a given object is not an element of a set and uses the symbol . For example given the previous examples set stating that is not an element of the set could be written as .