A data table alone has no axes, horizontal or otherwise. It consists of points of data; each point describes at least two pieces of information. Other points convey different numerical data about the ...

The X-axis, which is the horizontal axis, on most Excel charts does not use numeric intervals like the vertical Y-axis does. The X-axis contains either strings of text or a date under each set of data ...

Plotting a graph takes time. Often mathematicians just want to know the key features. These are: shape, location and some key points (such as where the graph crosses the axes or turning points).