A Relation denotes any kind of relationship / mapping between [[Set|sets]]. When not specified, it is assume 'Relation' refers to a [[Binary Relation]]. Formally, a [[Relation]] $R$ between two [[Set|sets]] $X,Y$ is a of set [[Ordered Pairs]] $(x,y)$ that defines a connection between elements of $X$ with elements of $Y$. Every relation $R$ between two sets $X,Y$ is a [[Subset|subset]] of the [[Cartesian Product|cartesian product]] of $X$ and $Y$. $ \large R \subset X \times Y $ The statement $(x,y) \in R$ is also denoted as $xRy$.