Labeling your graph is an important aspect of visualization, as the default variable names will not add clarity to the graph. ggplot has two ways to add labels and legends:
ggtitle(label): for adding the main titlexlab(label): for adding the x axis labelylab(label): for adding the y axis label
You can also use the labs(...) method to add all of these--the main title, axis labels, and even legend titles. In this recipe, you will learn about adding labels and legends to your plot by adding extra layers to it.