A graph is a calibrated representation of a mathematical or statistical state as applied to a particular issue or formula. Graphs are intended to provide a simple single image detailing relative factors in a particular situation. Many graphs are effectively charts of statistics, financial expenditure, etc, in which a graph can easily represent all elements related to the issues. In many cases graphs are used as progressive analytical tools for this purpose, simplifying reading and providing detail. Graphs can also be used as comparisons of different elements in a financial, statistical or demographic situation. 
Examples of Graph:
Finance Demography Statistics Mathematics Market surveys http://en.wikipedia.org/wiki/Graph_theory http://en.wikipedia.org/wiki/Graph http://simple.wikipedia.org/wiki/Graph 
This graph shows the unemployment rate by year in the United States. 
Cartesian graph paper. 
