—Data is the most important thing, and the thing that you bring to the table.
—Geometric objects … what you actually see on the plot: points, lines, polygons, etc.
—Statistics transform the data in many useful ways. For example, binning and counting to create a histogram. They are optional, but very useful.
—Scales map values in the data space to values in an aesthetic space, whether it be colour, or size, or shape. Scales also provide an inverse mapping: a legend.
—A coordinate system describes how data coordinates are mapped to the plane of the graphic. It also provides axes and gridlines to make it possible to read the graph.
— A facetting, or conditioning, speci