Definition:Symmetric Difference/Definition 1

Definition
The symmetric difference between two sets $S$ and $T$ is written $S \symdif T$ and is defined as:
 * $S \symdif T := \paren {S \setminus T} \cup \paren {T \setminus S}$

where:
 * $\setminus$ denotes set difference
 * $\cup$ denotes set union.

Also see

 * Equivalence of Definitions of Symmetric Difference