(related to Definition: Graph of a Function)
If $A$ and $B$ are the set of real numbers $A=B=\mathbb R$, the graph of a function $f:\mathbb R\mapsto \mathbb R$ can be drawn in a plane. In this case, the coordinates of the graph $(x,y)\in \Gamma_f$ are exactly the pairs of numbers $x,y\in \mathbb R$, for which $f(x)=y$. As an example, a graph of the function $y=f(x):=x^2$ is shown: