Taxonomy of Data Visualization Methods - Data Visualization: A Successful Design Process - page 117

Bar chart (or column chart)
Data variables : 1 x categorical, 1 x quantitative-ratio.
Visual variables : Length/height, color-hue.
Description : Bar charts convey data through the length or height of a bar, allowing
us to draw accurate comparisons between categories for both relative and absolute
values. When using length as the visual variable to represent a quantitative value it
is important to show the full extent of this property so always start the bar from the
zero point on the axis. The use of color can help draw attention to the values of specific
categories in accordance with your narrative, as shown in the following screenshot:
Floating bar (or Gantt chart)
Data variables : 1 x categorical-nominal, 2 x quantitative.
Visual variables : Position, length.