What is Graphing in science?

Graphing is a means originally invented by the French mathematician, Renee Descartes, by which mathematical data can be drawn and understood visually. It is used a lot in science. For example, if you wanted to show how nitrogen fertilizer effects the productivity of an Apple tree, you could obtain data for various levels of fertilizer and the corresponding quantity of Apples that result, and draw it on a graph, with the x axis being Apples, and the y axis being fertilizer.