This document defines common symbols used in set theory. It lists symbols such as curly brackets { } to denote a set, union (∪), intersection (∩), subset (⊆), proper subset (⊂), not a subset (⊄), superset (⊇), proper superset (⊃), not a superset (⊅), complement (c), difference (-), element of (∈), not element of (∉), empty set (Ø), power set (P(A)), equality (=), cardinality (|A|), such that (|), for all (∀), there exists (∃), therefore (∴) and defines types of numbers like natural