Theory:

Consider the following graph with some points plotted in it.
 
desmos_graph.png
 
Every coordinates \((5,2)\), \((3,-4)\), \((-1,2)\) and \((-3,-2)\) plotted in a graph represents the location of \(A\), \(B\), \(C\) and \(D\) respectively in the graph.
 
The coordinates are always return in a particular order ( \(x\) - coordinates (Abscissa) followed by \(y\) - coordinates (Ordinate)).
 
This is an example where we play with the number pairs in mathematics.
 
Such number pairs are called ordered pairs.
 
In set language, the ordered pairs play a major role in mathematizing relations.
Ordered pairs are a pair of numbers or elements written in a particular order within the parenthesis \((x,y)\).
The first element in the ordered pair represents the element from first set and the second element in the ordered pair represents the element from second set.